go to update your journal, write whatever you want to say and then go to "more options".
when you are able to put your mood and song and whatnot, near the begining, you will see an option that says "Journal to post in: (your username)--Default".
click on the little black arrow pointing down and there should be your default (your regular lj) and one that says "with_motion".
click on with_motion and then it should say "Journal to post in: with_motion" now you just go to update journal and its updated. ok?
anymore quetions, you can either comment here or just go to lj FAQ's.