1. If you can open the door wide enough to drill into the edge and into the frame, then bolts can be fitted without taking the door off. If your door can't be opened really wide, it is easier to exchange the hinges.
2. Security hinges and door hinge bolts differ slightly. Security hinges have one leaf with a couple of extra holes (in addition to the screw holes). The other leaf has metal folds, which close into the holes in the opposite side of the hinge. Door hinge bolts work on the same principle: a metal bolt fits into the door and a metal plate with a hole for the bolt fits into the door frame.
3. When you buy door hinge bolts, check that you have drill bits of the correct size. Use a pencil to mark out the bolts' position. Ask a friend to steady the door as you drill out the holes for the bolts. Do the same for the frame, then pencil round the metal plate and gently tap out the wood with a hammer and sharp wood chisel - the knack here is to work a little at a time and always keep your fingers behind the blade! Then screw on the plates and hammer in the bolts.
5. To fit security hinges, ask a friend to steady the door then take off just one hinge at a time. The screws might be stiff to undo - if so, try twisting them the wrong way to screw in rather than unscrew. This will help free them up without damaging the unscrewing side. As soon as the screws move, start unscrewing. Position the new hinge and use a sharp chisel to alter the fit and make recesses for the metal folds if needed. Screw on the hinge. Take care to hold the door firmly in position.