@Peter-Carr I aggree, with some common sense I was able do it, but I would urgently ask the Onion team to update their documentation. Obviously there are some differences in newer firmware versions like b233 I added a 1 GB SD-card. it was already formatted and automatically mounted. So I only had to start the slightly modified tar command and then I had to modify /etc/config/fstab file (But before that it took me hours and several firmware resets)