The XSheet is FlipBook’s timeline. Traditional animators use a vertical timeline because that’s how film goes through the projector. So every row is a frame and every column is a level. Levels are like layers but we stick with the traditional term because in FlipBook you can have layers inside of levels. The Background goes on the right and then the upper levels stack up to the left.

There are lots of ways to insert frames into the xsheet and they all start with selecting one or more frames at the point in the xsheet where you want the new frame(s) to go then, press the insert key if you have one. Or right-click on the row number and enter the number of frames you want to insert and the frame where you want to insert them. Then click on the Insert button. Or go to the Edit menu and select Insert.