Working with iMovie

Things have been going pretty well with my iMovie. I have figured out how to import movies, pictures, how to do voice-overs, and how to correct the view on images. I also have figured out how to rearrange things so that they can be in the right order. One issue that I am having, however, is that I don't know how to open a iMovie file that I have saved on my flash drive. I know that it is saved there, and that I have saved it correctly, but I am unable to open that file on a Mac other than the one that I have worked on it on. This is very frustrating. Also, I am not sure how to add a menu, an opening, or credits at the end. I am unsure as to how I can change the time limit on how long certain pictures are showing. I feel as though I am making progress, but it feels very slow and frustrating at times.