For this patteren you will need 9 threads, 3 strands of 3 colors.
Set up your strings so it is like 1,2,1,2,1,2,3,3,3. Lift your last string (3) and pull it up, out of the way.Take your strings 1,2 and do a forward knot. Do forward knots with all the pairs except the last strings (3,3).
Now take the first string (2) and pull it up, out of the way. Take the last string and pull it down. Take the strings 1,2 and do a forward knot. Do the same with the next pair of strings. When you get to strings 1 and 3 do a backward knot. Do the same for the next two (3,3).
Your strings should be set up like 2,2,1,2,1,3,1,3,3. Take the last string and pull it up and take the first sting and pull it down. Do forward knots with string pairs 2,2 and 1,2. Do backward knots with string pairs 1,3 and 1,3.
Take the last string and pull it down and take the first string and pull it up. If you didn't notice, your string order will be flipped from when you started (2,2,2,1,3,1,3,1,3), and so will the knots. Do a forward knot with strings 2 and 2, then backward knots with all the pairs of strings 1,3.
By now you should know about putting the first and last strings up and down. Each step will represent one row, for the odd number steps/rows the last will be up and the first will be down. For the even number steps/rows thr first will be up and the last will be down. Now take first string pair (2,2) and do a forward knot. Do the same with 2,3. With the next same string pairs 1,3 do backward knots.
If you did everything correctly, your strings should be set up like 2,2,3,2,3,1,3,1,1. With pairs 2,3 do a forward knot. Do the same with the next 2,3. Do backward knots with 1,3 and 1,1. Your string should be set up like 2,3,2,3,2,3,1,1,1. Notice anything? The order of the strings will not change but the colors will. That doesn't matter though, keep doing the same steps starting from the beginning and you will eventually start to see the pattern.
Here is the pattern picture:
If you still don't understand here are some videos (they do not belong to me) :
This one is really long because it does the same thing 3 times: