I wish you well in your new life here. One thing you need to realize, Nilufar is that you cannot rent a studio or one bedroom apartment for a family of four. You must have separate bedrooms for children of different sex. You can have an infant with you in your master bedroom, but occupancy laws will not allow for a family of four to live in one bedroom.
Depending on how old the children are and if they are of different sex, you should be looking for a two or three bedroom rental.