Help!!!

[sire]

I have recently started getting two pop-ups on my sreen re windows messenger. They come up when I switch on & even when I'm in the middle of a programme. One says Windows Messenger on the blue bar & underneath, exhorts me to enter the "name you want your contacts to see". The other is again Window Messenger & has my old service provider on it.
As a seventy six year old recycled teenager, I'm not very well versed in this IT business. Can anybody please tell me how I can get rid of these pop-ups. Thank you.

[TTG]

Launch Windows messenger and deselect the option to start it when Windows starts.