Welcome to the Asylum, please take a moment to introduce yourself here,
http://www.cigarasylum.com/vb/forumdisplay.php?f=7.
To check for a leak lift the top about three inches and let it drop. If it slams shut with a bang then there is a leak. It should close with a "whoosh" if the seal is good.
Check the stickies for how to season your humidor.