DD4T for .NET now supports the latest version of Tridion Sites: version 10. To upgrade, just replace the reference to your current DD4T provider package with DD4T.Providers.Tridion10.CIL.
DD4T (Dynamic Delivery for Tridion) enables the use of MVC frameworks in Java and .NET with Tridion. At its core, DD4T publishes Pages and Components as data into your Content Data Store rather than as code to your filesystem. You can then leverage tools which you know; such as ASP.NET MVC, Spring - or anything that can use REST to deliver your content in any view you like.
On our wiki you can find tutorials on how to get your first DD4T application set up. Learn how to use DD4T from scratch.
There are also instructions on how to setup your development environment, might you choose to contribute.
DD4T can be downloaded using NuGet (.NET) or from Maven Central (Java). There are also Zip packages available on GitHub for all projects.
You can download the template installer from Github as well.
DD4T is built by the community. So, we depend on people's own time to help develop new features and fix bugs. You can help too!