That’s not really enough information to go on. I’ve far too many questions to give useful advice.
However there are two patterns that might work depending on your specifics.
PRE-PUSH
You push the data from your system into the CMS first, and then it’s available to your user in the CMS anytime they want.
PUSH-ON-REQUEST
You wait for a request from the user
That request hits a webhook, which goes and gets the data and pushes it to the Webflow CMS, and then when the webhook returns you’d redirect the user to the new collection page.
If you want, you can use a 3rd party service to do the webhook and automation, rather than writing the webhook yourself- however, if you go that route you’d want one which allows you to separate the webhook request and the webhook response. I know Make and n8n can do this, and Zapier can not. Not sure about other platforms, and there are many.
Is there a way to push directly to the CMS using jquery on my Webflow page’s custom code? Or is this something I have to add to my backend using the Webflow API?
Webflow doesn’t allow this because you’d be forced into publicly exposing your private / secret Webflow API key within your jQuery on that Webflow page’s custom code.
That’s bad. So Webflow blocks you from doing it.
But yes to your second question. You’d have to go through a backend. But it doesn’t have to be your backend.
It’s fairly common to fire off a request into a free Make (Integromat) or (possibly paid) Zapier account which then pushes data into your Webflow CMS.
There’s also the option of Webflow’s new Logic feature, but it’s still in beta and can be a bit unstable at the moment.
Here are some tutorials & screencasts walking through how to wire all of this up (if you’re not already familiar with it):