I got a few question about this IDE.
First, when boot up vs2010, it displays some information below

I suppose that VS2010 Express is free to use but why it tell me it has 30 days limit?
Second, after I installed vs2010 express for windows phone, I also installed F# which is downloaded from here(InstallFSharp.msi). When the installation is completed I boot up vs2010 and I don’t see anything like template in the new project menu, Did I miss something?
Third, in this vs2010 express for windows phone, there is no such menu Tools->Extension, what can I do if I need to add some F# windows phone templates described in here?
And at last, I must apologize for my English, if the question here is not clear, please leave comment and I will try harder to make it explicit.
You need to register VS Express to continue to use it. I’m not 100% sure of why Microsoft put this in place, but they have. You have no choice but to register if you want to continue to use it. It’s not a big deal.
There is no Tools > Extensions menu in the Express editions as that is one of the restrictions Microsoft have put in place.