You can use the Razor Blade Tool to cut up your video and move the pieces around, or to remove parts of your sequence.
Drag a video from the Browser window into the Timeline.
In the Toolbox, select the Razor Blade Tool.
In the Timeline move the playhead to where you would like to cut your video.
Now place the Razor blade on this line in the Timeline and click.
Now move the Playhead to where you would like to make your next cut.
Place the Razor Blade tool on this line in the Timeline and click again.
The video in your timeline should now be divided into smaller pieces.
Choose the Selection Tool from the Timeline.
You can now click on the separate pieces of video in the timeline and delete them or move them around to rearrange the order of your film.