I just downloaded messenger on my lap top. My MESENGER iD is difrent from my Yahoo ID how do I log on to mesg

I have tried to log on, but it wont let me, it keeps asking me if I want to change the password for my main yahoo ID which I dont..i just dont know what else to do..thanks for any help!

I just downloaded messenger on my lap top. My MESENGER iD is difrent from my Yahoo ID how do I log on to mesg
It should be the same password as your yahoo mail. just simppilly change your password like adding the characters = !@#$%^%26amp;*()_+