write and read from firebase so that user cannot abuse that?

I have a web application. On the webpage user enter 2 IDs. I want to get those 2 IDs from my firebase database and then change some values of those objects with those IDs.

So I was wondering if there is a way to link my webpage with firebase (as in link them two together) and change data in firebase ONLY when the write is done from my web-app.

I am really noob on the back-end part, so all suggestions and tips are welcome, how to do the things I mentioned.