Once your app is approved by Apple App Store and wanted to set up the price you will have to login to iTunesConnect and select Manage Your Applications.
Once in Manage Your Applications, select the application name:
Once inside the App, click on Rights and Pricing:
Once in Rights and Pricing:
1. Select the Tier you want to set for pricing.
2. In the effective date selection, set to "Now"
3. In the end date selection, set to "None"
4. Select Save Changes
