the simplest way to start would be with php. you just need a text editor and either a hosting company like (
www.vilitas.com ) or just install it on your own computer and develop locally with your web server. ( IIS if you are running windows )
if you want to lean toward c#, then you will need to purchase a copy of Visual Studio. I think you can get the standard edition for about $100.
tell me which way you are leaning toward and maybe myself and other members can help you get your feet wet =)