Whether you are hanging bookshelves or breaking through the wall, you have got to know where the studs are inside it. There are three ways to find wall studs: 1) Sound it out; you should here a solid thunk when you hit a stud. 2) Look for nails along the baseboard. They are usually driven at stud intervals. 3) Use a magnetic finding device or "stud finder". It will zero in on the nails or screws that fix the wall to the stud.