Selling website connected to WHM?

Hello

We have a server with cPanel/WHM and the goal is to sell web hosting packages to the customers on our website. The problem is that I don't know how to connect a website and it's ordering system to WHM and our web hosting packages. How can we do this? Are there modules/plugins or ready to use websites which can be connected to WHM?

I have heard of WHMCS as billing automation, but does this do even web shop connection to WHM? Are there any other alternatives (preferably free alternatives)?

Thanks for help