What I'm trying to do is sync the BB and my GMail so everything gets updated. Right now, when I view my messages on my BB and delete them, I am able to delete them from both my BB and my mailbox. But when I try to delete them in my mailbox, they still appear on my BB and I have to go through all of them and manually delete each message. How can I sync it so it works both ways?
This is a known limitation of how Gmail is currently handled with BIS. Supposedly, sometime this Spring, this is going to be fixed so there will be syncing both ways, but until then, nothing you can do, sorry.
