the title is the question. no more.
In most cases, forum members will not generally be able (nor willing) to assist with requests of “How do I make X game”
However, as a small start I would probably recommend becoming familiar with collision, pathfinding, and variables as concepts and events.
You will likely need pathfinding for ghost movement, collision for handling dot collection and colliding with ghosts, and variables for everything dealing from powerups to score, and everything inbetween.
There are quite a few pathfinding examples included in the main engine, and most examples deal with collision of some kind. You can find out more about variables on the wiki.
The Pac Man game use a character move (up, down, laterals)
The map have walls to stop pacman (Not death touch)
Ghost have commands to find the player
Blinky - Search you with sound
Inky - Search a alternative route to escape from pac-man
Pinky - Search alternative route to find and kill you
Clide - Is the retard, no have route, random moves…)
The commands you can put in events, I don’t know more… for now.