From iMovie's menu select Share > Export Movie. Choose one of the preset sizes (resolutions), preferably the largest available. The sizes are Mobile, Medium, Large, HD 720p and HD 1080p. Any sizes that aren't supported by your movie will be greyed out. So, for example, if your project is in standard definition, the two HD options will not be available for exporting.
Select a location where to save the exported movie, such as the Desktop. The exported file will be in H.264 format which is universally supported. The file will have the extension .m4v or .mov depending on the size exported.
To share the movie with friends, there a several options. You could copy it to a USB flash drive for example. Or upload it to Facebook, YouTube or Vimeo. There are other sharing sites available also. Perhaps you have a Dropbox account or SkyDrive. Due to size constraints, videos are generally not suitable for emailing, so you should discount this option.
You could also use a DVD authoring program (such as iDVD or Burn) to burn DVDs for friends - but copying to a USB flash drive is best if your movie is in High Definition (DVDs are standard definition). USB flash drives can be plugged into any computer (Mac, Windows etc) or Media Player, allowing playback of video files.
The exported movie file can also be imported to iTunes (on your Mac or friends computers). If you or your friends have an Apple TV, you can then stream the movie from iTunes through Apple TV into a widescreen TV. If the original movie is in high definition, and you exported as HD, you will be able to view it in HD on the TV. The latest Apple TV devices allow 1080p (earlier versions were limited to 720p).
So, there are plenty of options for you!
JohnMacBook Pro (15-inch Late 2008), OS X Mountain Lion (10.8.3), Sony HDR-SR7 & DCR-TRV20E
I want to share the 15 minute movie I made on iMovie to a few of my friends. I am new to iMovie.
don't hesitate to read the manual
read about upload to YouTube; in YT, set your video to 'private'; invite your friends only ....