I'm close to clueless about DIY stuff involving cement, so I'd much
appreciate advice please.

The outer edge of bricks of my garden patio are falling away, as you see
from my illustration.
https://www.dropbox.com/s/e3ktr0m5d9...cks-2.jpg?dl=0

I've bought a 20 kg bag of ready mixed cement. But I'm not sure how best
to proceed after removing the dozen or so bricks. I assume I should just
even out the earth and lay cement over it, before replacing the bricks
on top. But roughly what depth of cement - 2 inches or so? And then just
press each brick down until its top is level with the intact bricks?
Presumably I should also slap some mortar on the sides of the bricks
before placing them?

Or should I first pack the strip of earth with smallish stones, gravel
or sand, instead of just laying the mortar directly over earth?

Although it's over 15 years old, I'm puzzled how it got to this state,
as I'd assume the builder laid a foundation under ALL the bricks,
including these at the edges. Maybe years of gardening has been a
factor...

Terry, East Grinstead, UK