Honestly the tutorials they have for the cheat engine, should be enough to teach you.
If you don't understand one try another there are several designed by various folks who use the engine. I was playing around with myself for the first time while waiting for this trainer to come out. I was able to boost Strength to 100; which only doubled the damage you did from weapons. I didn't check for level at the time, and the stats only used 2 bytes changes, but you have to lock the stat change in cause any time it checks them reset your stats to what your level should have it.. meaning anytime you look at them. (Also meaning you gonna have to re-hunt for them every time you play) There may be way to make the change more permanent that I don't know from my in-experience, but since they got the trainer out so fast I didn't play around with it for long. Though if you are already level 22 it be bit harder to find the proper but since most the hunting is based on finding changing values.
Just started a new game, and after about half an hour (on nightmare, should have tested on easy) I am now officially lvl 999. nothing goes beyond lvl 100 for attributes it seems though, but I haven't hit up vulgrim yet to buy equipment (I'll update after; if it works, I'll have some seriously impressive op armor).
Edit: Don't do lvl 999. Vulgrim can't sell anything.
Just tried lvl 100. The stats themselves go up accordingly on you, but vulgrim doesn't sell anything yet again. I'm getting the idea there's a pattern (there might not be anything beyond lvl 30 for gear). Also, tip, don't mod the lvl until you have all your unlocks (reaper unlock, evade, etc.) otherwise you'll never have it later.