please be more patient, wait at least 24 hours until you ask again.
You don't need an array for that, use ent_create in a loop like this:
int i,j;
i = _; // edge of field
while (i < _)
{
j = _;
while (j < _)
{
ent_create(vector(i, j, 0), _, _);
j += _;
}
i += _;
}
this code is not complete and untested, you need to replace the _ with fitting values for your game. It can create fields of enemies.
check ent_create in the manual if you don't know it yet.