Here are some pictures if you want a clearer picture:
See the notch in the middle? That is where the thread goes.
Here you can see where I have the thread
Pull the elastic thread over
Hold on to the thread that's on the needle and when you manually move the needle down and back up, gently pull on the thread you are holding and it will help bring the elastic all the way up. Put your machine back together and you are almost ready to go.
I set my tension on 9
and the length to 3.5
This is what it looks like after a few rows
If you have any questions, feel free to leave me a comment:)