I have created a solution for package importing POC in my local. So, I was following the steps at Import Pipeline Extension
But, I am not sure about step-1 where to perform it after creating the solution. Please suggest me.
Step 1 is in your JSS app's
/sitecore/definitions folder. Any of the component, route, etc definitions in here will work for this. By default
*.sitecore.ts are part of the manifest sourcing.
Step 2 and 3 are done in C#/Sitecore
Step 4 is within the JSS app.