Add video to start.

Add your videos from your files through clicking button "Add Video" at the lower-left corner of the interface. Or you can straightly drag the video to main screen. Both of them are very easy and convenient.

Set start and end to trim.

Click the button of "Set Start" and "Set End" to ensure your clip's length. Or you can set start to end by dragging the icon on the video moving contol line.