Subject says it all.
Please and Thank You,
Open the message, click the Labels icon. Think it's the middle one at the bottom, looks like a couple of dog tags. Then uncheck Inbox and check whichever folder you want it moved to.
The method described above simply attaches a label to a piece of mail, it does not move it, so the mail still appears in your inbox. In gmail on the web there are two options, 'move to folder' or 'label' that behave a little bit differently. In the Android app I can only figure out how to label, and not how to move to folder.