The below is a post from Rob Fitzpatrick in another thread so some of it's a little out of context, but I thought it was a fantastic summary of the resources available to the newbie Progress developer. I have therefore split it out.
Welcome to ProgressTalk! Well you found this place, so that's a very good first step. I think your next step should be diving into some documentation. As you said, you're not likely to find anything useful in your local book store, but there are available resources. Fortunately, the docs from Progress are available online and are pretty good for the most part. Here are the links to available online documentation. You can also download them in PDF or HTML form, which I would recommend as you will consult them a lot. As you are not using ABL by the sounds of it (ABL is the development language/runtime integrated into OpenEdge), you should focus on the general database info and SQL-specific info. So look at: Database Essentials, Database Administration, SQL Reference, SQL Development, and Basic Database Tools
Also on the subject of access to an OpenEdge database with the SQL engine, look into the UPDATE STATISTICS command. Bascially, it updates the metadata used by the SQL query optimizer, which will help your performance. It is also documented in the SQL Reference and the SQL Development guide, along with other query optimization info. You'll get a lot of hits if you search for UPDATE STATISTICS on ProgressTalk, mind you about 90% of them will be people saying things like "you'll get a lot of hits if you search for UPDATE STATISTICS on ProgressTalk".
If you have some budget for training resources, have a look at the Progress Books from BravePoint. I can recommend them personally as a great resource with a lot of practical advice for a newbie. BravePoint also sells a range of software products and utilities that integrate with OpenEdge (I have no affiliation with BravePoint; I just bought the books).
If you're going to be the go-to person in your shop for all things Progress, you will need to know how to monitor a running database. Get to know promon, which you already have as part of your Progress installation. Once you get your head around that, download ProTop and/or ProTop for .NET from Tom Bascom of DBAppraise (and White Star Software). (It's free!) You'll see a lot of posts from Tom on this forum. Also get to know SQL Explorer (sqlexp, a command-line query tool), which comes with Progress, or look into something third-party that is more full-featured like SQuirreL SQL.
Industry conferences are another great source of Progress information. Check out the videos and slide decks available online on a wide range of topics
And if you can sell your boss on attending a conference, check out PUG Challenge Americas 2013, June 9-12, in Westford MA, USA. Early-bird registration has already begun.
As you'll probably hear from others here, you aren't on the latest release of Progress OpenEdge. As you will see in the product lifecycle information, OpenEdge 10.1C is now about four years old; the latest release is 11.0 which came out in December. I don't know whether your company bought Progress directly or had it supplied from a vendor, but you may want to explore the possibility of moving to the latest release. If you can't, at least make sure you have the latest service pack for 10.1C which is SP04. To check, look for a text file called "version" in your OpenEdge installation directory. It contains a version string something like this:
OpenEdge Release 10.2B02 as of Wed Sep 1 19:14:44 EDT 2010
In this case the "02" after "10.2B" indicates that service pack 2 is installed. Make sure yours is 10.1C04.
You didn't indicate what platform you're on, so for some general advice:
Get to the latest OpenEdge release (11.0), if you can.
Always use a 64-bit OS on your DB server and the 64-bit Progress database binaries, if you can.
Get to know your DB server platform(s), in terms of OS and hardware, storage sub-system in particular. It's the slowest part of your system, so it will have a big impact on your performance profile. Note your RAID level(s), if any. RAID 1, good. RAID 10, great. RAID 5 (and other parity-based variants): eeeevil. Avoid it like the plague.
The database ("OpenEdge RDBMS", in marketing terms) comes in three license flavours: Personal, Workgroup, and Enterprise. Get Enterprise if you can, otherwise your performance-tuning options will be somewhat limited. To check your installed products, run "Start | Programs | OpenEdge | Config" (in Windows) or "showcfg progress.cfg" from your OpenEdge installation directory (in *nix).
You have likely inherited some databases of questionable or unknown health, maintenance record, and level of tuning/optimization. Read up on database startup parameters in the Database Administration manual; some relatively small changes in a badly-tuned database can make a big performance difference in some cases.
In that same manual, look into structure files (which map out the physical storage used by the database) and understand the difference between Type I and Type II storage. Once you grasp that, inventory your databases and make sure they all use Type II storage areas for all application data. If they don't, start on a plan to migrate them to Type II (this involves a dump and load of your data, and index rebuilds). As a bonus, dump/load/rebuild will also help with performance degradation due to physical scatter, record fragmentation, and low index utilization. To gauge your databases' general state with respect to these metrics, look into the "proutil" command with the "dbanalys","tabanalys", and "idxanalys" qualifiers (in the reference section at the end of the manual).
Do your homework and ask lots of informed questions. People here will be happy to help you.
For other web resources, check out all of the links here.