Whenever searching for fireteam on bungie.net, they provide a battltag they want you to add. I tried searching on google, but there is no such tutorial. How to use it to send friend requests?
The Battletag consists of an Username and an ID. Like this: Username#2622
You can only add friends on the Battle.net Client which you have to install first.
If you already have the Battle.Net Client installed: To add a friend you have to go to your Battle.net Client and click on your name on the top right. There should be an Add Friend Button in this Window.
If you don't have the Battle.net Client installed:
Go to the Battle.net Website.
Login to your Battle.Net Account and go to Account Settings > Games & Codes > Download Clients.
- Scroll down and you should find Blizzard Battle.net® app and download the client.