Chain 5, then chain 3. The 3 create the first DC in your cluster.
Cluster - chain 3 (already done) plus 3 DC together. This is basically doing the first part of a DC, and not finishing it, but going on and making all the first halves, until all your DCs are on the hook, waiting for the final half of the DC, which pulls them together into one cluster stitch. (I hope that made sense!)
Anyway, here are instructions for the DC together: yarn over (yo), insert the hook back into the chain, yo, draw the yarn through the stitch, yo, draw the yarn through 2 loops on the hook.
Repeat the DC together stitch until you have 4 loops on your hook. Yo, pull through all the loops. Cluster completed!
Repeat the cluster - 3 DC, 3 DC together. Now you have two clusters next to each other. Slip stitch into the top of the first cluster, pulling the two halves into a little ball.
Chain 5. Slip stitch into your project. I like to make mine 4 stitches apart.
Repeat from the beginning - chain 5, chain 3, cluster, chain 3, cluster, slip stitch the clusters together, chain 5 slip stitch to the project.