People will tell you strange things.
The Taurus 940 will be an adequate IDPA pistol as long as it is reliable in operation; it meets the rules.
Now all you need is a strong side straight draw holster, at least three magazines and belt carrier(s) for two of them. They need not be fancy, kydex rigid synthetic is better than flabby nylon, though.
Plus, of course, eye and ear protection; and a concealment garment of some sort. Do some dryfire practice safely drawing your gun out from under a jacket before you do it with ammo.
If you carry it cocked and locked it will enter in ESP division; if decocked for a double action first shot it can shoot in SSP division.
I have four priorities:
1. Be safe. Don't hurt anybody, don't scare anybody, don't get disqualified for a safety rule violation. Say you are new and ask for familiarization.
2. Execute. Each course of fire (CoF) has specific requirements. Understand them and shoot it right, without Procedural Error penalties. Be sure what Tactical Priority and Tactial Sequence mean, when and how you can reload, how to use cover, what spread hands on a target mean, etc.
3. Hit the target. Hit it in the middle (or head if required.)
4. Move along. Your time from start to finish is your score, plus add-ons for points down and penalties. Don't run before you walk, LITERALLY, but don't dawdle around, either.