Once you are logged in to Sku Grid, navigate to Settings. Click on Marketplaces. Click Amazon. Click the Country you are selling on. 

On this screen is where you will enter your Amazon developer keys. It is important to note that you must be an Amazon Pro Seller and paying Amazon's monthly fee in order to access your Amazon Keys and use Sku Grid. Click the link that says Click Here to be redirected to get your Amazon Keys. 

Fill in your username and password to log into Seller Central. If you have Two Factor Authentication turned on, you'll need to retreive the security code from your Authenticator App on your mobile device.  If you do not have Two Factor Authentication turned on, you can ignore this step. 

Proceed to Sign In. You will now be on the User Permissions Page of your Seller Central Account. 

Copy your Seller ID and paste it into the Amazon Merchant ID field in Sku Grid. Be sure that when pasting in your values into your Keys settings that you are not pasting in any extra white space or characters before or after your keys; otherwise, they would be invalid. 

Next, click the following link to be redirected to Amazon MWS Endpoints and Marketplace IDs. Under Amazon MWS MarketplaceIds, you will see a table that shows the 2 letter abbreviation for the Countries that have Amazon Marketplaces. Find your country code in the list and copy the Marketplace ID that is shown right next to it.Go to your Sku Grid tab of your browser and paste the Amazon Marketplace ID in the corresponding field.Next, go to your Amazon tab in your browser and Toggle back to the Amazon tab in your web browser and in the section that says Amazon MWS Developer Permissions, you will see Current Authorizations.  You will see a row there with your store name and in parentheses it will say (You). Note: If you do not see your store name in this list of current authorizations, you will need to register as a Developer first. This just means that you may not have ever had any software tools linked to your Amazon account and therefore don't have a developer account.   You do not need sku grid's developer key. The keys used in sku grid are your own. If you need help figuring out how to register as a developer, please visit https://docs.developer.amazonservices.com/en_US/dev_guide/DG_Registering.html for more information.

Click the View your credentials link in that row.  These are your developer access keys. Copy your Amazon Access Key then click back to the Sku Grid tab of your browser and paste it into the corresponding field.Then click back to the Amazon Tab in your browser and click the View link to reveal your Amazon Secret Key. Copy the Secret Key. Click back to the Sku Grid Tab of your browser and paste in the Secret Key into the corresponding field. Next, type in your Amazon Store Name, exactly how it is, however, do not use special symbols or punctuation. 

For example, if your store name is Joe's Crab Shack, you would just type Joes Crab Shack with no apostrophe.Scroll down and Save the Settings. If you ever need to disconnect clear your Amazon Keys, you can do so at that top of this page by clicking the Disconnect button.