Ecommerce & Marketplace On Shopify

I need an online marketplace platform where buyers and sellers can transact for ANYTHING.

I have the domains, trademarks, etc. etc. now I just need the Web and Mobile apps.

I want to use Shopify as the platform for all ecommerce/transactions (marketplace format).

I hope to acquire a Mobile and Web app Wireframe or Mockup, maybe a template, that can be easily altered or customized by me as to what I need EXACTLY. I will do that editing myself.

Obviously, there will be 2 components: Front End (end user) and Back End (admin control panel).

Once I finalize the Wireframe or Mockup template (design/flow/process), then I will need to finalize development and launch.

Does this make sense? Is there anything I am missing or do you have any questions? Any feedback or input is appreciated. Plan for now:

Step One:
1) A Shopify ecommerce (Web and Mobile) Wireframe or Mockup template for me to edit.

Step Two:
2) Develop, test and launch

PLEASE DO NOT AUTO ME and KNOW FULLY what I need or ask me.... I will reply ONLY to those who are credible. Thank you.