My wheels wont fit my car? What can I do?

Hi, I bought these MSR wheels for my ford mustang on Ebay. Even though they were 5 lug wheels and my car is a 5 lug as well, the wheels were to small. Is there any type of devise that I can buy that would make em fit? LIke a wheels adjustment spacer? Please let me know. I really want these wheels. THanks