Help with a GFCI outlet?

sounds like you are over your head. The incoming power is the line on the gfi. if it is backwards it won't work right. the load side is like the load on a tow truck it carries the stuff you want it to. any black from there must have it's accompanying white on the load side as well. a gfi looks at the black wire and says is this the same as the white coming back. if not it turns off. likely you put your line and loads reversed try that first. past that i fear you are lost.