Do not use wooden posts, they will only last 5 years or so.

Drill holes along the vetical centre line, into the concrete, as
there are normally 4 steel rods that go down the 4 corners.

I have just done 2 seperate jobs, each with gates on.

In all cases do not hang the gate on the post if you can help it.

1st job - Concreted well in a concrete post, then fixed a wooden post
infront of it (not concreted in), by using long 180mm x 6mm csk
screws, screwed in thro the holes in the concrete post, from the back
face where the panels slot in. Then used the wood post to fix the
correct wood battening to it. If you have the right sized wood you
circular saw out the rebate for the gate.

2nd job - Used the concrete post inner edge as the slamming part of
the gate, added an additional wooden battening to the edge of the
panel to fix the gate latch etc. OK this was not ment to be a very
secure gate, but it served its purpose.