Getting started with WordPress

I am wanting to build a WP site but not sure how to begin and what themes/plugins/extras to use.
I will just give a basic rundown of my idea with ‘VEGETABLES” as the product instead of the real product I wish to use in the end

The site I envisage will be Australia wide, people advertise their “vegetables” for sale by creating a profile, with a photo of vegetables, price and contact details, The customer goes to the site and looks up their local area to see what vegetables are available in their local area

So, The site would work off lots of profiles geosorted
if someone could suggesst a theme based on profiles and a way to geolocate sort it would be much appreciated