Download and user account creation

I am planning to start new responsive page. I have a few queries.

  1. I am planning to start free and purchase wallpapers application. I need the option to download images and as well paid one.
  2. user can create his account and he can upload the products(images) in the application. This option is must and should.

where can I find these above 2 options? I am ready to purchase.

Please help us.

What do you mean by application? Some CMS , Android , IOS etc?

its cms

You have plenty wordpress templates who is support multivendor plugin. Only you know what template is good for you.