Packman

If you've already installed RISC OS RC5 on your Raspberry Pi, you do not have to burn a new SD card with dd to get RC6. You can use PackMan.

A.K.A. Pacman meet Cyrano de Bergerac

I thought you said Puckman

!PackMan is the package manager for RISC OS. It will connect to a repository and download your selections, or perform an upgrade.

Bundled apps, including !PackMan

The Packman user guide is here:
https://www.riscosopen.org/wiki/documentation/show/PackMan%20User%27s%20Guide

Note that after the upgrade, your config.txt will be overwritten, so if you made modifications (for the hdmi modes or the memory split), make a note of them.