Hope this makes it a bit clearer?
- Foundation chain is the row of chain stitches you always have to do to begin a piece of work.
- Crochet 15 chains (12 +3 for turning chain).
- Turn work and yarn round hook to begin a treble, this goes into the 4th stitch from the hook. Create one more treble, this is the first cluster (including the 3 chain stitches that are your first treble)
- Crochet 1 chain, skip a foundation chain stitch and now crochet 3 trebbles into the next chain stitch of the foundation row. Keep going until you reach the end. Here only crochet one treble.
- Turn work, crochet 3 chain stitches and then 2 more into the nearest space (gap).
- One chain stitch, skip one foundation chain stitch and 3 trebles into next chain stitch.. keep going as long as you like.