hello,
i can help you to setup a website and a webshop to sell hosting and vps.
i've done that many times.
this is not so easy task and will depend on what you have and what you wish.
you can sell a shared hosting accounts based on Plesk/Cpanel/direct Admin and similar control panels.
this can be done automatically.
for a vps , well, there a big choice on what and how you can sell this.
if you want to sell manually --> any virtualization is a good choice.
if you want to do that automatically so there is some choices.
SWSOFT virtuozzo/Proxmox/OpenVZ and some hosting companies who have some pluggins.
there also some setup on DNs side for customers need to be done.
if you have any questions don't hesitate to contact me.
have a good day