What version of iMovie are you using? iMovie '11 (with an apostrophe) is iMovie 9. There is no iMovie 11 (without apostrophe). Possibly did you mean to say iMovie 10, that is the most current version?
You can send a copy to a friend of a standalone iMovie video that you have shared out. Drag it to a thumb flash drive that is formatted ExFat in case your friend has a windows computer. If he/she has a Mac then format it Mac OS Extended (Journaled) or ExFat. Then give the thumb drive to your friend to play on his Mac.
If the movie is not too large (under 5 GB) you can email it with the free iCloud Email account that you can set up on your computer.
Assuming that you are using iMovie 10, for the transfer of still editable iMovie projects (as opposed to the standalone movie) between Macs you need to transfer the iMovie library that contains the project. Put a copy of the library on an external drive or thumb drive that is formatted Mac OS Extended (Journaled) and then transfer the drive from one Mac to another. The resolution will preserved. If your projects are still in iMovie 9, you can open iMovie 10 on your Mac and do an Edit/Update Projects and Events, that will create the projects in the iMovie 10 library. Then follow the above transfer procedure.
Here's a link to a help tutorial that explains how to transfer libraries and projects:
https://help.apple.com/imovie/mac/10.1/#/mov3fa25bae7
-- Rich