Chabad tying is actually a bit tricky at first, but hopefully you'll get the hang of it quickly. Most of our customers have us tie the tzitzit from start to finish, and I'm always worry about how they are are going to deal with tzitzit coming a bit untied if they don't know how to tie according to their own custom.
The Chabad tzitzit tying pattern is like this:
double knot, 3 windings, 3 windings, 1 winding, double knot
2 windings, 3 windings, 3 windings, double knot
3 windings, 3 windings, 3 windings, 2 windings, double knot
1 winding, 3 windings, 3 windings, 3 windings, 3 windings, double knot
Grand Total: 39 windings, 5 double knots
The concept behnd Chabad tzitzit is that you essentially are essentially tying 13 chulyos (a chulya is a group of three windings), only two of them are "interrupted" by a double knot. Why 13? The Gemara explicitly states that tzitzit must have a minimum of 7 and a maximum of 13 chulyos.
So how do you make these chulyos?
First, set up shop by finding something heavy to keep the corner you're working on firmly in place. For example, a table lamp, an unabridged dictionary or a laptop.
This is going to sound really complicated in black and white, but it's actually quite simple, so don't be alarmed. Take hold of all of the tzitzit except the shamash (the longer one) in your left hand, and grasp them with your pinkie and ring finger, extending your middle finger and index finger straight, behind the seven tzitzit and pointing to the right.
Bring the shamash behind your left index finger and then down below your left middle finger, then pull the shamash to the left, passing in front of the other seven strings. Using your right index finger, press the shamash on your left index finger. Not gently and slowly move that left index finger a little bit out of the way and pull the shamash through the loop so that it's parallel with your left middle finger. (By the way, up until this point it's exactly the same as Sephardic tzitzit tying.)
Stop and catch your breath. Now you're going to do exactly the same thing another two times, but just make sure the second winding is above the first one, which may sound a bit counter-intuitive.
That probably sounded complicated, but in practice it's not. Now comes the tricky part. Your task is to pull this chulyah tight while keeping those three windings you created nice and neat. This takes a bit of coordination. I pull the shamash tight a bit at a time, while gently holding my windings in place with my left thumb and right index finger.
You now have one chulyah done. The only thing keeping it tight is the next chulyah, so don't head off for a coffee break right now. Make a second chulyah of three windings, just like the first one, and then make a chulyah with just one winding and then tie a double knot. Great! You've finished the first of four sections. To continue, refer to the pattern outlined above before we started tying.
How hard is it to tie Chabad tzitzit? If you have good fine motor skills, you will probably get the hang of it in just a few minutes, and the total process will take 10-15 minutes per corner your first time through.
Here's a video to illustrate Chabad tzitzit tying, but I can't promise you'll be able to see the technique very clearly.