Well, my 2p on this is, especially for beginners, is dont try to update from 2.6 to a newer version, as the paths and some key files differ dramatically.
I would be tempted to use 3 beta 4, then for a start you will find that lr-pcsx-rearmed is already installed (I dont remember if it is or not on 2.6)
When you download and use an image, all the emulators will be already installed and ready to use (except for the experimental ones).
Here is a vid:
Try writing 3 beta 4 to your card, then dont update the binaries or script, as there shouldnt really be a need unless you want to get an update to something thats fixed since late June. Plus if you are on a specific version like 3 beta 4, its easier to get support as everyone will know exactly what your setup is.