Need some very basic help

[CleverFellow]

I'm just starting to try to work my own php into my templates, and I'm a bit confused about how you make variables available to templates using {vb raw} and {vb rawphrase}. Once I've made my variable in the php file, do I need to add it to a special class or something? And I read somewhere that you need to pre-register variables to use them in templates in 4.0 - does this apply to this situation?

Thanks a lot