Dave Richards (a.k.a. AA7EE) has a nice write-up about building another Si5351 VFO project:
To many, this will be just another Si5351 VFO project, with nothing to distinguish it from the others. In fact, that’s exactly what it is. The “how to” of connecting an Arduino board to an Si5351 board, wiring up a display, and loading the firmware, is straightforward, and well established. To me though, it was a complete mystery.
See the full post on his blog here.