The API Details page gives the urls to use minus any query parameters or headers that you may need. Here is a copy of one of my API proxies. I pointed out the url that would be used for a particular flow;

For example, if I want Joke Detail, I would use
http://mikemalloy-prod.apigee.net/training/joke?jokeid=3229 (or some other number). The ?jokeid=3229 is something I provide because the API requires a jokeid query parameter to work. If you need to supply header information, that must be done through the console.