C# is an object-oriented language created and maintained by Microsoft. It is very similar to Java in many ways, however, since it is proprietary, the development ecosystem for C# applications is much more closed. You'll have fewer choices of tools and frameworks. In particular, you'll be working with the VisualStudio IDE. C# / .NET are used primarily in larger companies.
Start by learning the basics of C#, and then move on to learning ASP.NET, the MVC web framework for building web applications in C#.
- Learn C# language basics
- Syntax
- Types
- Control structures
- permissions / access control
- Learn object-oriented concepts
- Classes: properties and methods
- Access modifiers: public, protected, internal, private
- Polymorphism, inheritance, encapsulation
- Learn ASP.NET
The time to learn these tasks can be highly variable, depending on which resources you use, how many hours per week you are able to devote to learning, and what type of support you have (online via message boards, in-person at meetups, etc). Focus on learning all of these topics, rather than hitting the specified number of hours.