I'm interested in what type of parallax effect you're trying to achieve. I previously posted on this topic at this link: http://forum.webflow.com/t/parallax-without-code-no-copy-paste-no-custom-css-no-custom-js/13981/3
I happen to be personally in favor of first trying to use the built-in tools in webflow to at the least simulate a parallax effect though whether it's accurate to call it parallax might be debatable rather than first resorting to some custom code. In my mind, when websites are called parallax sites, different animations happen upon scrolling.
My technique is to create a div that acts as a trigger to start the various animations. This div would initially be positioned outside the viewport or outside of the page, for example, just below the page. So, you'd position that div, and then attach a scroll interaction to it (in the "Scroll Into View" section with "Affect Other Elements" checked, and then type in the name you've given to the other element. Keep clicking the plus sign button to add more scroll interactions for other element. Then, make that element do something like move down. Don't forget to reverse whatever the effect is by setting the Scroll out of view parameters.
To summarize the technique briefly, start with a section that's sized as 100vh height. You might call this section the home section. Below that, create a new section. Within that new section, place a div, probably positioned at the top of that section, you might call that the Trigger Div. When that Div scrolls into view you can have various animations occur. You can see my work-in-progress site where I'm employing this technique in the link above. Definitely let me know your thoughts on this, if you think this is a good or not good technique. And let me know if you decide to use it yourself.