The D-Link WBR-1310 is a very old router, I would suggest an upgrade. However, if you wish to continue using it....
The wireless password is whatever you set up when you configured the router. If you don't remember or it was never configured for wireless, then log into the router at http://192.168.0.1. The default userid is "admin" and the default password is blank (ie. leave the field blank). If you changed the password when you setup the router, enter your password. If you don't know the password (and leaving it blank also doesn't work), then reset the router to factory defaults, log in with a blank password, and then proceed.
Once logged in, click on Setup, then Wireless Settings on the left and follow the instructions in your manual (page 25, page 44, and page 46-47), to configure your wireless network. Essentially, you will name the network by providing an SSID, choose your encryption type (WPA2-PSK is best, do NOT use WEP it's not secure), and provide a passphrase for wireless users to use your router. This last is the part you seem to be missing. Make sure your Cipher type is AES and your choose PSK (not EAP). By default the channel is 6 and you should leave it there unless you run into interference or congestion from other routers or wireless devices like cordless phones.
I also advise you to change your admin password as well, Tools -> Admin to do that.
Then write these passwords down in a safe place.
To reset the router when you can't login, press the Reset button in the back until the lights flash on the front. This changes all settings back to the why they were when the router was shipped, so if you have any custom settings, they will be lost, so you will have to re-apply them.