how can i find out what power is good to what distance. Also, i'm trying to find some info on all the functions of scopes. Thanks from a noob to long distance
Really depends on the Optics, the better the Optics the lower the power needs to be. But as a general rule 1 x 100 is a good start. If your trying to benchrest you might want to look for more power, 22-25+ power for 1000 isn't uncommon.
Once you really get to shooting you'll start to develop preferences. Things like max power on scopes can be a subjective thing. 12X on a high end is enough to see targets way out there where as 20X on a POS you may not see well very far. Everybody is different and sees things differently, get behind as many as you can and see for yourself.