what kind of contract to sign

[Grace Sunshine]

I located a vacant property with poor condition. The owner is out-state and would like to retail it. However, with current house condition, it is hard to get price she asked (it is already listed for a year and expired twice). We agreed that I will pay the cost to rehab the house and list the house for sale. She will get money she asked for after the rehabbed house is sold. This is a brand-new business model for me. What kind of contract should I sign with her? Any samples here? Thanks very much.