How do I make waves of enemies?

im making a top down game where i have to defend a base from enemies coming from all sides, but i don't know how to make them spawn in waves

You can use a timer or other means to determine when they will spawn and then use a repeat loop to spawn a large number of enemies in a certain area.

Example:

On timer "wavespawn"

sub event: Repeat 10 times - Create object "enemy" at X [random(viewportleft-100, viewportleft+100)], Y [random(viewportleft-100, viewportleft+100)]

clone this sub event 3 more times and use viewport top, bottom and right.

Hello again, im very new at this and i don't know how to setup the timer, do i need to make a code for it?

You can add the timer behaviour to any of your objects that are in the layout. Then in your events you can set the length of the timer, whether it repeats or not, and assign it a tag so you can reference that timer in other events. Then you can start and stop the timer with events.

More info here on the timer: construct.net/en/make-games/manuals/construct-3/behavior-reference/timer