If students are working in groups, set aside one or more class periods as needed for each group to present its work in front of the class. If the entire class performs together, you may just do one read-through, or you may rehearse and then present your play to a selected audience (another class, the parents, etc.). No props or costumes are necessary, but if you wish to add a little "window dressing" you may certainly feel free to do so - arranging the readers in a certain setting or using classroom items and furniture to suggest different props and scenes.