do i need to bleed the cooling system when i replace the thermostat?!?!

yes. There is a screw on top of of the t-stat housing. Take out the screw and fill the radiator through the radiator where the cap would go. When you get a steady flow coming out the screw hole, put the screw back in, radiator cap back on and fill the coolant overflow jug to the bottom of the cold mark. Run the car and keep an eye on the overflow jug level for a couple of days.

awsome thanks thats wat i thought but i dindt feel like doin it haha im lazy...

If you can't get anymore in the rad and it still doesn't come out of the bleed hole on the top of the thermostat housing.....give the rad a blow job.
Yes seriously..
Pinch the overflow bottle hose and blow into the rad cap to blow the air out until coolant comes out...squirt...squirt...
Don't laugh. It works. Try it.