In order to establish your connection, you'll need a number to connect to. If you're using a CDMA or EvDO BlackBerry phone (one that runs on the Verizon Wireless or Sprint networks), the number should be *777.
If you're using a GPRS, EDGE, or UMTS BlackBerry (one that runs on the AT&T or T-Mobile networks), the number should be *99.
If these numbers don't work, check with your cellular carrier. They may be able to provide you with an alternate number.
You'll also need a user name and password from your cellular carrier. If you don't know it, call them and ask how to find it.
You'll also want to give this newly-created connection a name that will allow you to identify it in the future, such as BlackBerry Modem. Enter this name in the "Connection name" field at the bottom of the page.
You can test the connection if you'd like. Whether or not you test it now, make sure to save it so you'll have all of the information you just entered.