The way you move forward with finding the right people and team to work with will depend on your situation. Here are a few examples and scenarios:

Scenario 1: You have a good friend or know someone who is a top notch designer. You may wish to work with him or her on the design elements and outsource the rest of the development to a separate developer or development team. This may leave you to manage the communication between design and development.

Scenario 2: You want everything managed by a single team, from design to development and project management. The advantage of working with a full development team is that everything is in one place and communication may be slightly easier as you are playing less of a middle man.

Scenario 3: You decide to find separate resources to work on your app. You source a designer and developer seperatley.

Scenario 4: You have a low budget and decide to look for 'less expensive' offshore resources.

Scenario 5: You would like to meet your team and work with them in person as needed so you source a team local to your area.

Project Management:

Don't underestimate how much time you should put aside for the management of the project. Whilst you have done your best to clearly outline all aspects of the app with wireframes etc, remember that you will be required to make decisions, provide feedback and test your app throughout the process. You could always outsource this project management process if you are short on time. A great free tool to keep everything on track and organized visually is Trello.com