Will these rims fit my car?

I have found a set of rims locally on craigslist. I want to put them on my 1998 Mitsubishi Eclipse Spyder GS. The stock wheels that are on there now have 5 lug-nuts. I don't know much about wheels. What size do these wheels need to be to fit on my car? What kind of things do I need to ask the seller to insure that they will fit on my car?