Hi @Sergey, see this post:
If you are wanting to achieve a parallax scrolling that goes beyond using fixed background images alone, you can look at some jquery plugins:
https://plugins.jquery.com/tag/parallax/
Webflow allows you to set a fixed background image on a section (like you have in your design). To get a real parallax scrolling effect to work, you need some script for that. You can put your custom script in the Footer section of your Custom Code tab in Site Settings.
I hope that helps. If you have exported your site, and plan to put it on your own server, then I would recommend uploading that, then sharing the link, so we can see what your site looks like when published, and what errors there are, if any. Cheers, Dave