incline is were you are on a bench and the back piece is diagnoled up ward, kinda like your on a reclining chair at a beach.
decline is the opposite, the back piece is all the way back and down, so your head and spine are pointing down. (incline and decline is hard to explain online and nothing you shoul worry about right now lol)
females will not get big muscles no matter how hard or long you work out for haha the girls that you see in magazines who are all jacked and bigger then most men are all using steroids, that how they get that big, so you dont have to worry about that.
a cheap and effecting way to tune your upper body (i would still work out your lower body because although cardio is good, resistance trainning(weight lifting) will tone out your legs way more and better then running will. and im tanlking in a slim lady like way (no big muscles lol)) would be to buy some dumb bells and a stability ball
then you can look online for different work outs