I need a yahoo messenger.?

sadly they took that away years ago.

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

how do you chat with friends on yahoo fantasy sports then.. is it done too ?

No, you don't. Verizon terminated it over a year ago. You cannot email other YA people even if your email is enabled. Verizon disabled that 2 years ago.

I'm afraid you're way too late. Verizon has closed it down more than a year ago.