an easy way to remember which way to shift is: when you move the "metal" shift lever, the chain moves in the same direction (works for both front and rear derailer). So think about how you want to move the chain, (harder larger higher) gear in the front, or (easier larger lower) gear in the back. As for "trim" there are several posts here that explain it. But for the most part you probably won't use it much. For the most part, trim is only used is in "rolling" hill areas. If you live in New England or other areas where there are lots of hills, you will never need "trim" (because you use both the largest and smallest chainring frequently. Trim is only used on the middle chainring, and only if you go the full range of the rear derailer.