Before you buy a book, look online at some tutorials and see if you like the language first, that way if the language is not for you, you will not have spent money on anything.
Don't worry there are too many ways to learn asp.net with yourself. But most convinient is to first download the latest version of asp.net then use the book with author Wrox and it is good one.......Also you can take a help of W3school...
You can learn everything about ASP.NET from the following ASP.net Book by Charles Carroll
- VB.net Beginner Samples
- ASP.NET 2.0 General Lessons
Otherwise you can visit the following site.. w3school and Lynda.