Here's how to open your join requests (you'll get more members if you do):
Click on 'Admin Area'
Click on 'Manage Members'
Click on 'Members'
Now there should be a place that says 'Join Requests', with a drop-down menu under it. Click on the drop down, and select either 'Are Always Approved' or 'Are Subject to Vote'. If you pick the first one, everyone who applies will automatically be approved. If you click on the voting option, you (and any other mods) will be able to vote yes or no on whether each applicant can be a member. Then just click 'save settings'.
Good luck!