The format devines the specifications of your video: size, framerate, video codec.
Video sharing platforms can handle most video formats. So it is best to not change the size of framerate of your video.
Look for an option in your editing software to export the video optimized for online sharing.
You can also find help about the best format to upload from YouTube or vimeo directly.

YouTube is the most know video sharing Platform today. It is a good place to have your video uploaded since you can share it easily with other YouTube users.

vimeo looks like a fancy version of YouTube and focuses more on video art. The quality of the uploaded video is good and the embedded player looks more professional then YouTube. Try it out.