With Share -> Other
If you have a Twitter App installed on your phone then go to the Map display.
(To display pics, see Introduction  for how to take pics with comments and tags)

Press the green Share button and select Other to display the list of Share Apps available on your phone.

If you have a Twitter App on your phone select it (on this phone the Twitter App is TweetCaster)

Enter your comment (if you wish) then press the attachment symbol to display above. Make your selection. 
To upload the Map picture, select Add Photo and select your Map picture from the Camera Album. It will be the latest picture added.

Follow the instructions and you Map picture will be uploaded to Twitter.