how to use class of other project in a solution (internal)?

Question

Environment :

In C#, I have a solution with many project. They were added with *.csproj files.

Problem :

In a project, you can use classes of other files through namespace. However, is there a way to use namespace and classes of another project in the same solution?

Answer 1

In visual studio you should have a "References" area in the Solution Explorer. Right click that and click "Add Reference..."
From here, it's just a matter of locating where you other code is on your machine.

Edit: Here is some additional information on DLLs, in case it helps you.