Two approaches: indeed you can use a Browser source. Once you've added that source to your scene, when you select it: click Interact (or right click at the source and select Interact from the context menu). Now a window pops up in which you can interact with the website. (If applicable, don't forget to check Properties, Control audio via OBS to have the website's sound in your stream/recording.)
Or you can open the website in your browser and use a Window Capture source. Now the interacting can be done the usual way in your browser. (If applicable, also add an Audio Output Capture for the browser content's sound.)