50 is the number of "the great expansion," of which only 49 is used.
Pick one of the 50 sticks and place is across the table in front of you. This chosen one symbolizes the taiji.
Randomly divide the remaining 40 into two groups holding one group in each hand.
This procedure symbolizes the "two manifestations," yin and yang.
Put down the ones in your right hand in a lower corner of the table, pick one from it, and place it between the fourth and the fifth fingers of your left hand.
The sticks in your left hand symbolize heaven, the ones you put down on the table from your right hand symbolize the earth, and the one you chose from those sticks and placed between the fourth and the fifth finger of your left hand symbolizes humans.
These three are called sancai (three talents/materials/powers/agents).
Count the ones in your left hand, not including the one between the fourth and fifth fingers, by fours.
Place what remains (1, 2, 3 or 4) between the third and the fourth fingers.
The number "four" symbolizes the four seasons.
The remainder that goes between the fingers represents intercalary months.
Pick up the sticks that you had put down in the lower corner of the table from your right hand in step 3.
Divide them by fours, and place the remaining (1, 2, 3, or 4) between the second and the third fingers of your left hand.
Put down the ones that have been placed between the fingers on the first stick that you put down as you began casting.
Using the remainder of the sticks, repeat the procedures 2-6. When you put down the sticks placed between fingers, do not mix them with the ones you put down in 6.
Using the remaining sticks, again repeat the procedures 2-6. When you put down the sticks placed between fingers, do not mix them with the ones you put down in 6 and 7.
Now you have three groups of sticks placed across the first stick.
First group is either 9 or 5; second and third groups are either 4 or 8.
Write down the three numbers.
The following guidelines will help you determine the marking based on the combination of the numbers.
(9, 8, 8): old-yin
(9, 8, 4) or (5, 8, 8): young-yang
(9, 4, 4) or (5, 8, 4): young-yin
(5, 4, 4): old-yang
Write down the marking.
You have just completed the casting of the first line, which is the line at the bottom of the hexagraph.
This means that, to get one hexagraph, you need to repeat six times the process described in 1-10.
If all six lines are "young" lines, the hexagraph you obtained is not "moving-to" another hexagraph.
If any of the six lines are "old," the hexagraph you obtained may "move to" another hexagraph.
Interpretations can be found here or in any copy of the Yijing.
Interpretations are partially based on the combinations of trigrams that make up the hexagram (described from top down):