An 'instance' is a 'dungeon'.
When you did them, did your group gather together in one of the major cities and all go together? Or did you meet at the instance entrance? If you haven't used the LFG tool yet, I strongly urge you to try it. It's a lot easier than trying to set something up on your server. With the tool you can just queue yourself for a level-appropriate instance and it'll put an icon next to your minimap. You can also continue doing whatever else you might be doing. That way you don't have to wait in a city/town for a group to form. And when the tool has found 1 healer, 1 tank, and 3 dps, it'll alert you and works as a "ready check". To which then you'll be teleported inside the instance. When the instance is done (or whenever you want) you can click the icon on your minimap to get the option to "teleport out of the instance" and it'll put your exactly right back where it left you.
I know you're more into solo play, and I am too, but if you want the gear you desire you're gonna have to do some stuff with other people.