To Manage App Section,

1. Go to the Magento 2 Admin panel.
2. On the left navigation bar, click the SELLERCENTER INTEGRATION Menu.
   The menu appears as shown in the figure:
   
3. Click on Manage Apps.
   The Sellercenter Account Page appears as shown:
   
4. Click on Add New Account.
   The Add New Account page appears as:
   
5. Now under Account Information, do the following steps:
   • In the Account Version, the version of the account will be displayed.
   • In the Account Name, enter the name of the account.
   • In Marketplace, select the marketplace from the list.
   • In the Username, enter the username of the account.
   • In the API Key enter the API copied from the seller panel.
   • And then click on Validate for the validation/checking the account details entered.
6. Now under Store, select the store view in Default Store.
7. Click on Save Button.
   The account will be created.