Formal:
* Faites votre lit. (This is the most direct translation and is appropriate for formal settings.)
Informal:
* Range ton lit. (This is more casual and can be used with friends or family.)
* Fais ton lit. (This is also informal and is more common than "range ton lit".)
Important note: The verb "faire" (to do) is used more often in everyday conversation than "ranger" (to put away).