General steps for all systems:
1.Enter Programming Mode [ ...BUT....select the right mode for the job. There are at least two modes on each system, one for appointing an 'address' to the decoder, the other for telling each decoder what characteristics you want it to 'play' for you so your locomotives behave as you'd like them to.]
2. Once the decoder accepts the address you assign it (you're calling it a name, and most of us use the cab number because they're all likely different...unique to each locomotive model you own. Makes it easy.), you switch 'naming mode' and tell the decoder what volume you want it in Master Volume, what momentum and inertia rates you want (slow for drag engines, maybe faster for passenger commuters that are short, and about the same for powerful tractive locos like the GG1).
3. You exit programming mode, and you play and note what you still want to improve. Re-enter programming (the right mode....remember)...ALWAYS verify you're in the correct mode before you press another button!!! You acquire the CV you think needs fiddling, change values, press 'enter', Exit programming, and then see if that improved the behaviour.
That's all programming is. Digitrax, although it has a comprehensive manual that seems daunting, is relatively straightforward. Heck, it worked for me, and I'm no engineer or physicist. Just deal with it. Open manual, look at diagrammes, read instructions, pick up the real item, and start pressing buttons. You learn visually, auditorially, and tactilely...so do all three ways and you'll eventually get it.
Make sure you redo programming several times. Reset one or two decoders, and try it all again....BEFORE the sun sets. You want this to be familiar before you try it again next day. By the end of the first week, you'll know precisely how to manipulate your decoders. NOTE- not all decoders follow conventions on what they assign to Function buttons. LokSound, for example, does NOT MAP its bells and horns to the same buttons as you'll find on the TCS and Tsunamis, as an example. Hey, they have to keep your brain young and you on your toes!
READ THE X$#& manual.
Be very certain that you're in the RIGHT PROGRAMMING MODE....BEFORE you press another button. Why? Read the manual. Says right in there.