Where and how I can get this url in future

I completed Create a Candidate Rating Flow  unit in Automate Business Processes for a Recruiting App. 

And we used this url.      /flow/New_Review?varJobAppId={!Job_Application__c.Id}&retURL=/{!Job_Application__c.Id}   to create o button based on flow. 

Can somebody explaine where and how I can get it by myself in future.