To embed Google Analytics tracker, first:
1) Log in https://mixform.com/login
2) Click Design on the left
3) Scroll down and click Edit Third Party Options
4) Enter your google analytics tracker id (it looks like UA-xxxxx-x, the x's are numbers, you can find it by looking at the embed code they provided you)
Hi there! This is Mixform's help site. Here you can find articles on how to use Mixform, and check the latest updates and issues. Send me an e-mail if you can't find what you are looking for. --Deb