Assuming you have added the reference to the web cameras DLL file...
Take out the line:
Then compile your program - you will get errors.
GO to the first error and put the cursor in the first word that is underlined in red. A small blue box will appear at the beginning of the word. Hover the mouse over the box, and a dropdown will appear. Open the drop down, and it will have possible solutions to the problem. The first one should be "using ..." select it and it will add the using statement for you. Repeat this until your references are correct.