If you go here:
http://www.microsoftvirtualacademy.com/training-courses/windows-phone-8-1-development-for-absolute-beginners[
^] it runs you though a tutorial on how to do it. And you need the VS templates for windows phone apps - which I don't believe are available for VS2008.
However, VS2013 has them, and it is available in a
Community Edition[
^] which is free to developers (provided your company is small enough, or you are a one man band). And it does have teh templates.
So I'd start by upgrading VS and work from there.