Trimming excess imported video

I am trying to build an animation over a video layer. I only need a couple hundred frames located in the middle of the video. I understand how to clip off the portion of the video after the frames I need, using that little red slider, but I also want to clip off the beginning hundred-or-so frames prior to those I need. I don’t see a similar slider at the beginning of the timeline for that purpose. I know that the imported video becomes a series of png still frames, so I just need a handy way of doing away with the excess at the front of the clip. Any suggestions?