ok thanks parthos , so the rear springs just go right in no need for compression, and i also think i see insulators or something in the rear springs..will i need a new one as well and is there a certain kind of mount and insulator i need for my balt? i found some at rockauto but they looked different$800 is way too much.
You do not need new front mounts unless yours are worn badly. It'd probably make the job a bit easier if you got them though. You could take the mounts, front springs, and struts to a shop and have them assemble them. That way, no spring compressor would be needed. Just direct bolt in at that point.
You'll need a spring compressor, a ratchet set and a torque wrench (just to be safe; Walmart has them fairly cheap). Mounts attach directly to the top of the struts. When the car's jacked up, and there's no load on the rear springs, you can get them out relatively easily compressing them by hand. Getting the rubber mount off can be a little difficult, but not impossible. Here's a couple of pretty good videos of what needs to be done:
How To Install Replace Front Strut and Spring Chevy Cobalt Pontiac G5 05-10 1AAuto.com - YouTube
How to replace Shock Absorbers on a Chevy Cobalt - YouTube
Replace Rear Coil Springs - Chevy Cobalt - YouTube