OK it depends.
If you have a finished movie, you can SHARE/EXPORT MOVIE and create your final movie. Then, depending on the size of the finished movie, you can transfer via dropbox or similar service. Ninety minutes is a very long movie for iMovie, but it may work for you. I would suggest 720P to keep the size down.
If you need to transfer the entire iMovie Project so it can be edited in iMovie at the other end, then you need to transfer the project and event assets to an external hard drive and get the hard drive to the other location.
Directions are here. Follow the directions for 1) Moving or copying Project to external drive. Then 2) Consolidate Media.
https://discussions.apple.com/docs/DOC-4141