How can I get someones MSN address with just there first and last name?

The thing is It's a girl, and if you've read my other question 'Does this girl love me?' you would know why. It was my last day of school (YES!) and she wasn't at school that day. So I couldn't ask for her MSN address. Later that day I over heard some girls (I am not nosey they talk quite loudly) and they said that that day was her last day. :(. Please help me.