Now assemble your ridge pole.
There are a few places in this greenhouse where I recommend pinning the connection so it doesn't come loose later; this is one of them. The elbow connectors on your primary ribs are another. If you live in a windy area, you might want to pin all connections.

The method by which I do this is shown:
Lightly spray the pipe ends with cooking spray. Butter flavor works best.
Insert the pipe into the connector, and pound it all the way in with a small mallet.
Drill 1/8" holes through the center of where the pipe and connector form a double layer in the joint.
Insert a zip tie through the holes and zip it tight.
Now the connector can't pop off, and when you want to take down the greenhouse, all you do is cut the zip tie.

Assemble each pair of ribs and its elbow connector the same way. They should form a 90' angle, which you will bend later. Be sure that the connections are all snug using your mallet. Mine is named The Persuader.
You should now have one 20' ridge pole 3/4" diameter, 3 primary rib pairs 3/4" diameter, and 8 secondary rib pairs, 1/2" diameter.

Pics:
1- Pipe ends with cooking spray, yum yum
2- Straight coupler shown with one side pinned and the other side just a hole that doesn't even go all the way through (battery on crappy Craftsman cordless died... I swear cordless power tools are totally marketed towards chicks. I made the switch to corded everything about a week after I bought my house hahahahaha!!!!).