Easy to follow steps for Creating an app to Integrate with 3rd party Quickbooks

Hello community

Could someone please explain the step by step process in laymans terminology of creating an app in order to integrate with a 3rd party in particular quick books?

What i have managed till now are the following:

I create an OAuth2 app, i assign the classic scopes and all the app related scopes from the granular scopes, i am sharing the app, i have used a random callback id in the authorization, for example goole.com, i have the Classic Jira platform REST API authorization URL and when i paste this in a browser i get the prompt to installthe app, which i accept. Then cheking in Myapps , i cannot find this app.

Could someone explain what is wrong in all this and maybe provide the steps of what should i do in order to provide to the 3rd party a connection of their connector to jira?

Thanks in advance