如何存储JavaScript文件并在.NET中调用以使用Ajax

I am newish to coding and am working on a project in Visual Studio 2010 using VB. I want to implement Ajax in my solution and I think that I have to use .js files to do this. My question is, provided I can get appropriate JavaScripts to build the files, how should I store them in my solution and how do I actually call a class that I have created. I presume the .js file would be separate to the .aspx and .aspx.vb files. Any assistance would be appreciated. I am newish to coding and am working on a proje