Just a word of caution on those plastic covered greenhouses: A strong wind will pull that cover off in no time! I think I have the exact same one, bought as an overflow area for when the tomato plants get out of control (as they always do!). If you get much wind where you are, you'll need to come up with a better way to secure the cover.
Other than that, Rick has provided some very thorough information on seed starting in general. We could be more helpful if you mentioned what plants you were planning on starting.
