Sometimes I read a page filled with jargon that I think might be a good introduction to a science fiction novel. Familiar words are used in unfamiliar ways, such that you can almost but not quite figure out the meaning from the context. Urbit's breach page is the last I recall like that. If you are self-hosting your ship, following these instructions is mandatory in order to communicate with the rest of the network.

I’m self-hosted—what do I need to do?

You are still in the old era. You need to download the correct OTA from ~fet, a galaxy that Tlon has left running in the old era specifically for this purpose. Enter |ota ~fet %kids into dojo and wait until the OTA update is complete. Now you are ready to proceed. The implication of this writing is some really good world-building, even though that wasn't the intent at all.