Step 1:
Click on apps-> App and Sales channel

Step 2:
Click on Develop Apps


Step 3:
Click on Build Apps in Dev Dashboard

Step 4:
Click on Create App
Step 5:
Enter App name and click Create


Step 6:
Enter your shopify store url, uncheck Embedd app in Shopify store checkbox and select required scopes

Step 7:
Click on Home menu and click on Install button, Select your store and install it


Step 8:
Click on Settings page and Copy Client ID Secret. Open https://kodxshopify.com/saveapikey and enter your shopify store url, Client ID and Secret then submit.