You need to use the getLoggedInAthlete API call to get information about the logged in athlete (in this case you). The data returned from that call contains a list of your clubs (club IDs) and gear (gear IDs). You can use those values in the other API calls to retrieve more detailed information.
As far as segment IDs, you need to find the specific segment ID you want to get more detail on. There are a few different ways to do that.