hi, i want to create an entity that follows the player. i create the new entity by ent_create but it stand still and i want to move it along with the player. and also when i press the key to run the ent_create funcition it creates many new entities as the key is pressed, and i just want to create one

Just give the created entity the Funktion:

regarding the multiple creations:
it sounds like your create_entity is inside your while loop
you should call create_entity before your while loop in the player action
this will create the entity right after the player entity is created

untested pseudocode

If you want to directly connect the entity to the player
just use a vec_for_vertex command like:
vec_for_vertex(me.x, Pointer, 182);
it will connect the entity to that vertex
on the entity you typed into the command.