How to communicate directly with Geth package API/SSH through dappnode?

I downloaded the Geth package, everything works well in terms of the Sync and the configuration but I can’t understand how am I supposed to communicate with the Geth API / Cmd ?

This is the same for all packages, I can get to the Dappnode SSH but I can’t move on to the applications in it.

Can anyone please help me understand what am I missing?