- You can right click inside the folder(that needs to be copied) in windows explorer and click Ctrl+A or select all the files and click copy.
- In the FileSystem editor, navigate to the the left side. Then right click on the application folder and click Add and select folder.
- Give the name to the folder
- On the right side of the FileSystem editor, right click and select Paste
- All the contents of the folder will get copied into the newly created folder in step 2.
For further information, refer following link
https://dzone.com/articles/creating-msisetup-package-c