Video editing help desired

Perhaps this is worthy of a blog post, but how in the world do you take a 5 minute video clip out of a 90 minute video so as to make a 5-minute highlight video? I can't seem to have 2 open videos at the same time so as to copy and paste from one mega long video into a smaller video.  Presently, I'm taking the long video and making a copy of it. Then with the copy, I delete all the other segments. Then save. Then export the highlight video.  There must be a better way.  + +   As I edit the mega long video, I'd love to be able to drop a note in text or hashtag or even a STAR system to know that this segment is a keeper and ideal of later edits. When I put a text subtitle, then I cut a video segment before the one with the text subtitle the alignment of the subtitle is gone. So, the videos all slide to the left, but the subtitles do not. HELP.