sun ultra

Hi Guys,

I have a 2nd hand Sun ultra-5, I wanted to know how to be able to run it as a normal window. I do not have any experience whatsoever with solaris/unix. Does anyone can give me a clue where to start. When I switch it goes to:
unix console login:
pa$$word:
#UNIX sendmail [198]: enable to qualify my own domain name

Any help

Thanks