Create online store

Hello, Nobita.
How long!!!
I hope you are very well.
I wanted to ask you if with the Rainbs theme I can add an online store.
If so, I imagine that I would have to create a new theme, with a new domain.
Could you inform me, please, on this subject and what would be the steps to follow?
Thank you very much, as always, for your kindness.
Happy week.

The page I need help with: [log in to see the link]