iMovie: How do I select & save a couple clips taken from a large video file?

I have a MacAir. I have latest version of iMovie. I'm new to iMovie & have a frustrating problem. I looked all over the web & can't find a solution. I have several long raw video files that are 1 hour each. I'm trying to select clips from the raw footage to save them. I can't figure out how to do it the way I was hoping I could. Let's say the clip is 0:00 - 60:00 long. If I want to cut & save section 10:15-11:20 I can't seem to find a way to save just that small piece of the file without deleting section 0:00-10:14 & 11:21-60:00 then saving the clip since its the only thing left. To make my next edit I have to reload the whole darn raw file again & repeat the steps above. Isn't there a way to take a long video file & make multiple clip/cuts along that file & save just those clips without having to delete everything in front or the clip & after the clip? Seem like an obvious feature to have but I'm not finding it. I have hours of footage to edit if I have to load file-edit- delete section- save clip & repeat process it's going to take forever!!! :-(