I've had a few questions lately about how to set up a heddle rod.
When I was first learning how to weave, I searched for a heddle tutorial high and low and couldn't find anything! I had to do some experimenting before I understood exactly what they were. See those two dowels at the top of my loom? Those are heddles... and they will change your weaving life.
Before you can set up a heddle rod, you need two things. First you need to create a number of leashes. These are pieces of string that are tied in a loop so that they all have the same diameter. To make it easy I put two nails into a piece of wood and tied of my string to be sure that each loom has the same measurement. I keep this wood around so that I can make more leashes whenever I need.
Now comes the part to set up your heddle!
1. On your warped loom attach about four leashes to the warp. Using your finger to hold them in place, slide the middle of a leash underneath a warp string and back up so that both ends are together. When you pull up on both ends of your leash the warp string will come up as well. Be sure to skip every other warp string as your are looping the leashes on.
2. Slide the ends of the leashes off of your finger and onto your heddle rod.
3. Using the same technique described in step 1, slide your leashes, one by one, skipping every other one, through the next couple of warp strings. Use your finger to hold them in place.
4. Slide the ends of the leashes off of your finger and onto the same heddle rod.
Continue doing this until you have reached the end of your warp and every other warp string is attached to your heddle with a leash.
Do the same thing with your second heddle. This time be sure to attach the opposite warp strings (the ones that weren't attached to the last set of leashes).
As you can see below, when you lift up one heddle, the first set of warp strings lift up with it. They leave a gap that makes it so much easier to slide your needle through. Likewise, when you lift up the other heddle, the opposite set of warp strings will lift up as well.
The first thing to know about heddles is that they are completely optional. If you work on a small loom they might even be unnecessary. If you prefer to use a shed stick (the brown, wide stick at the top of my loom below) then you only need one heddle. You can see with my first frame loom that I used a knitting needle as my heddle and taped the leashes so they wouldn't slide off.
It all depends on what works best for you!