I just replaced my doors last week. I have a house that was built in 1951. It is a pier and beam foundation.
What kind of foundation is your house? (slab or pier and beam)
The first step is to go in the attic and look to see if the wall is supporting the roof. You can tell by finding the header of the closet and making sure that there is not any 2x4's nailed to support the roof.
Next you must tear out the drywall to reveal the framing. Built braces to hold the header in place.