Movie Maker

This is my first time trying this.  I have it together but want to add/subtract different pictures.  I cannot get to the spot where the pictures show up together where they can be moved or deleted.  At the front of the first pix is a black stripe (that looks like old 35mm film strip) and the last pix has it, too.  Everytime I try to open it, all it does is make another video with all the same pictures.  I'm sure it's something easy but I tried all the possible options at the top and can't figure it out.  Very frustrating!  Any help would be appreciated.  And again, this is my first time so please use language I will understand!