If you built the MVP but don't have customers yet, you should already have some people in mind who suffer from the problem your solution is supposed to solve. Selling is then just a conversation that loosely follows the following steps:
(a) Ask if they still have the problem
(b) Ask if your proposed solution solves their problem
(c) Ask them to spend money to buy your solution
Note that every step starts with "ask". This means that you need to listen to their response. If they don't still have the problem, walk away. If your proposed solution doesn't solve their problem, listen to why not, and focus on improving your product until it does solve their problem (hopefully in a generic way such that your improvements will help you sell to other customers in the future). If they aren't willing to spend the price you're asking to buy a solution that they consider to be a solution to a problem they have, then find a way to add more value so that they will be willing to pay that price.