There are all kinds of ways to make gravy, there are tedious "french" ways and there just plain wrong ways. I do it the easiest, tasting good way. Now the foundation to a good gravy is the drippings to which your meat cooked in, and if you well seasoned your meat, your gravy will also be seasoned well.
Let it be known, my blog has become a family affair. I have a director and producer now, and I didn't even hire them. My husband, whom I call "coach" because he is always "coaching" me on everything, even when he doesn't know crap, has made himself the director. My friend Don, who is video producer by profession (see here) suggested I post a video on my blog, so he pulled out some serious gear at Sunday dinner last week. The director really wanted to do a second take, he had some serious issues with the impromptu script, but the food was done, it was time to eat. I have my priorities. So here is our youtube debut.
So your turkey might not have enough liquid in the drippings, and since you used a roaster, you will need to pour everything into a sauce pan, try to scrape as much of the brown bits and possible. Add potato water if you need more liquid, you could also add a little butter or cream. Make sure you taste it!