How to share Sonar files to a friend using Logic??

The difficulty depends on how many tracks you have. Do you really need to send each track separately?
If your friend will, say, only add a guitar solo or vocals, you can send an MP3 to him, and he records his part in full wav quality, and sends those tracks to you to be added into the project.

Otherwise you must export every track as a separate wav, and your friend must re-assemble the project in Logic. In such a case it's practical to make every track start from measure 1, that way your friend doesn't need to manually position the tracks.

In case Logic reads OMF-files, you can export the project as OMF.
 
EDIT: Oops. I noticed you send it for mixing. Then you must have a mutual understanding about effects, for example. If you use FX, which are then printed in the wavs, it can be tricky for your friend to add more FX.

So Audio files are easy, but if your tracks are MIDI then you have to make a few choices. 
If you have a VST that he doesn't have then you will have to sort that out. 
Either bounce the MIDI track to an audio track or find a VST with a similar sound in his collection. 

Rod I woul stem the audio and NOT OMF. OMF transfers can be a nightmare especially on limited studio time.

Hope this helps.