i want to get these installed at a dealer, but buying off the net is cheaper...

i looked on crutchfield and they have the speakers as a component that comes with a tweeter....i dunno much about this stuff but i want to replace all 4 doors...i dont need 4 tweeters....dont make fun of me if im totally clueless about this stuff...


also when i goto the installer...is there anything i needa tell the installer specifically when i drop off my car?