The grene dorge is a six loop braid decribed in a 15th century manuscript. It is interpreted as either of two or three colors. If you are doing a three color version you will need four loops of one color and one loop each of the other two colors. For instance if you wanted a cord with green on the outside and a orange and yellow dashed line down the middle you would use four loops of green, one loop of orange, and one loop of yellow. The fingers are lettered ABCD starting with the index finger, so as examples RA would be the right index finger and LC would be the left ring finger. The movements generally involve sticking an open finger through one or two loops to grab a loop off of a different finger. If the instructions say to take a loop reversed that means to take the loop such that the bottom part of the loop becomes the top part on the new finger. The other common movement is to switch a loop from one finger to another in order to create an open finger.
Start out with the loops in the following configuration:
LA - Yellow RA -
B - Green B - Green
C - Green C - Green
D - D - Orange
Repeat the following five steps:
1. RA through RB & RC takes LC reversed
2. Switch LB to LC
3. LB through LC takes RC reversed
4. LA takes RD and RD takes LA
5. Switch RB to RC and RA to RB
In practice I tend to combine steps 2 & 3 into a single motion.
Also the two loops that make the center line (yellow and orange) tend to get used a bit faster than the others, so I compensate by making them a little longer to start. For a two foot length I might make these loops a half inch longer and they will end up a half inch shorter by the time I am done.
If you are interested in the various braids I highly recommend the Compleat Anachronist #108. The braids are based on material from the 15th century manuscript (Harleian 2320) and several 17th-century manuscripts (V&A
86FF3, V&A T 313-1960, V&A 1-1012-1938 and 86FF4). Among other things I find their notation system much easier to understand than that of Speiser.