The Choose Extras screen is used to pick from the list of Extras, those appearing in the shot. Click on the desired Extra and then on the ‘<’ button to move the Extra from the "All Extras" list to the "Extras Used" list. You can also double-click on the Extras’ name or if you want to add all the Extras use the "<<" button.

Removing Extras works the same way, by double-clicking or using the ">" and ">>" buttons.

Click the "New Extra" button to add Props to the "All Extras " list.