any suggestions...

i had a few questions for anyone who can help. i've been messing with ps for a while but i can't seem to transport a car/truck out of the picture into a blank layer without it having messed up edges, even with a high resolution pic, any suggestions? i also have been messing with colors and the only thing i can't figure out is how to change the whole color instead of the tint of the existing color. i have a few other questions but i'll see if anyne can help me out wiht these ones first. thanks for any help, always apperciated. - Jason