Installing new head unit..

Hi, i am planning on getting a new HU and doing it myself on my 4 door 1990 Eighty Eight Royale.
I already put some audiobahn 6x9's in the rear(i hate the way they are mounted with the big box that comes out) but did not replace the wiring(dont know how to).

I want to order online from car domain because they are a lot cheaper and it comes with everything you need to install.

My question is, for a car audio beginner, how hard would it be to do this?? What do i need to do to take the old one out? The wiring the new one in should be easy because it is simpily taking all the wires out of the old and putting in the new right?(with a wiring harness of course)

putting a head unit in is real easy especially if you spend a little extra money, i mean the dash kit and wiring harness.....im not familiar with the dash for the '90 88 but most olds and buicks you need to take off the dash panel and then unbolt the radio, disconnect, plug in a new one and voila....most likely there will be a few bolts holding some trim around the panel and then everything else pops out....get your new radio and new harness and connect everything inside your house or garage on a table(its just more confortable) make sure your dash kit looks like the outside of your radio (bolt holes line up), bolt it up and remember to get the antenna adapter, on the new radio and harness all the wires are color coded so its hard to mess up, and unless you are getting a very very expensive radio you will not need the accesory/dimmer wires...orange and orange w/white tracer if i remember right......blue w/white tracer i think is the remote wire for your pwr ant or amp, its better not to hook up your amp to this, it sux to listen to amplified buzz if you took your cd out and left it on a radio station that sux....go for it, its good experience and those $30 or $40 buck you save can be used for more speakers

yeah i need 3.5 in the dash. Thanks BTW! That was the best answer out of all the threads i posted. heh

THX again..

no prob