How I Can Import & Use Existing C# Class Library Project>

If you are using Visual Studio, click "Project->Add Reference.." and select the tab "Browse". Now in the file browser, select the output file of your Class Library(.dll). Now you should be able to explore the class of your library in "Class View".

Note: If you add the class library to the same solution which contains the WinForms project, instead of going to the browse tab, go to the "Project" tab and select the class library project name.

1) create main folder

2) put both of your codes in same folder (class library project and window application)

3) now open window application and create solution file from new menu and save in Main folder.

4) right click your solution file and click Add --> Existing Project --> go to your folder of class library and select project file.

5)once project is added to the solution, you need to add reference to your window application.

6)now right click your window application and click Add Reference

7)select solution and check your class library project. and press OK.

8) Rebuild your solution.

9) you can use now class and objects of class library with the use of Using statement at top of the c# page