Including variable in a URL

Here's the issue... I have a URL that needs to include a user's email address. I have the user enter their email address and set that as a variable. I then need to add that variable to a static URL: www.domain.com/userid=[variable]courseid=2. I believe I need to use javascript to do this but don't know how to execute it and frankly where to begin. Any insights, advice would be greatly appreciated it.