How to upgrade from .NET Framework 1.0 to .NET Framework 4.0

Can you please let me know the steps to upgrade Dot Web Application from .NET Framework 1.0 to .NET Framework 3.5 or 4.0.

Details about current Application

I have gone through the below link ,but stuck with first point

https://blogs.msdn.microsoft.com/pandrew/2007/10/25/how-to-upgrade-from-net-framework-1-0-to-net-framework-3-5/

Stuck point : First upgrade your code from .NET 1.0 to .NET 1.1 using Visual Studio 2003. It has a project upgrade tool with some assistance.