It's super clear.
Here is another perspective
The main difference that might confuse you is that the old round solenoids were most likely body grounded, where the top post solenoids are most likely post grounded. The small 'S' post is the switch input, the OTHER small post is the ground.
I was able to re-use my copper connecting plates when I converted the 8274 to top posts. had to drill a new hole in two of them and trim the extra, but that was easy, copper is soft.
The rest of the wiring on these is identical to any 4 solenoid setup. The only difference is that you have to ground each one with the small posts or the switch (S) circuit will not work.