Watch this video from This Old House to learn how fix a unbalanced door.
1 Close door and check the spacing at the top and latch-side of the door.
2 Determine which hinge must be shimmed to adjust door and create even spacing.
3 Remove appropriate hinge from door and jamb.
4 Hold door hinge against cardboard and use utility knife to cut around hinge; cut several shims.
5 Set two or three cardboard shims in the hinge mortises on the door and jamb, then replace the hinge.
6 Install shims behind other hinges, if necessary.
7 Close the door and check the spacing.
8 If necessary, add or subtract shims until the door latches properly and closes without binding.