Yahoo messenger is an instant messaging application. You need to add someone Yahoo messenger contact list to chat and call with them. Learn how to add someone on Yahoo messenger contact list.
1. Sing In into yahoo messenger using your yahoo email address and password.
2. After sign in yahoo messenger you see yahoo messenger dialog box with your yahoo email address. Click Add a contact icon to add your friend into yahoo messenger.

3. A new dialog box will open. Type your friends email address into Enter a Messenger ID or email address blank box. I typed my friend email address. You don’t type this email address. You type your own friend email address and click Next button.

4. You see new dialog box click Next > button again.
5. You see a massage that your email has been added to your Messenger List and Address Book, pending his or her response to your request. Click Finish button to finish this process.
6. You see your recent pending request on your yahoo messenger friends list.

All process you complete. If your friend accepts your request then you can chat and share with them everything. You can audio call and video call with him/her.