Choose "File" and then "Import." Navigate to the footage of the explosion and import it into your video editing software. This procedure is the same for Adobe Premiere, Avid and Final Cut Pro. If you don't have footage of an explosion, download free sample footage from an effects site.
Drag your subject footage to the timeline window.
Drag your explosion footage to the timeline window and place it on the video track above the subject footage.
Check to see if the background of your explosion is already transparent. Some software will automatically activate the alpha channel and make the background transparent. If your background is not transparent, select your explosion footage and activate the alpha channel. Choose "Modify," "Alpha Type," and then "Straight." Some software refers to "Alpha Type" under the menu "Clip." If your explosion footage does not have an alpha channel, choose "Modify," "Alpha Type" and "Black." Your video editing software will use the color black as if it were an alpha channel.
Adjust the size and position of your explosion to suit your needs.