How can i have friends without using yahoo messenger ?

You go out in real time and talk to people who share your interests. Not everything has to be done online. Messenger was disabled quite a while ago anyway (in 2012 or 2013). There are also other methods of communicating with friends such as facebook (where you can use facetime), Ooovoo, Vimeo, youtube, snapchat, Instagram, and I am sure many more that will give you the opportunity to chat as much as you want to.

There is no Yahoo messenger

Walk down the street to their houses and knock on the front door.

Instant messenger no longer exists. It was closed in July 2018: https://help.yahoo.com/kb/SLN28776.html