Been passing this around for almost a month now, but for those that didn't hear it from me or others, posting the link here
You create a tag with you ID, either for people to invite you, or join you
You can also /join their ID in game if their tag description fits your needs
Make sure you are not in the EU tab if you are playing on US because you won't be able to join the same instance.
I find pugging really useful now and then because you can learn a lot of tricks from a variety of players, and when no one is available in the family.
This site was really how I become so proficient at dungeons, just be ready to have a tough skin on because now and then you will run into bad groups :s But that is not unexpected so can be prepared for.
Remember to have good manners and patience!