The original text of the apache license can be found here:
A good explanation is given by the team of the original java based zxing:
I think the important point is that following:
"A common way to comply, in a product that is delivered only in binary form and not source form (e.g. an application download) is to add a mention of the project, and link to its license (in our view, a link to the project website is ultimately also fine),
in a "Help" or "About" screen of the application."
You can find a lot of samples for different target frameworks of .Net in the source code repository.
Look at it and play with it. They are simple and powerful.