A new garage door is not a weekend kit job, and we'll say that plainly. The panel itself isn't the hard part - it's the torsion spring under tension, the cable drums, and getting the track plumb against a frame that's had sixty-plus years to settle slightly out of square. Get the spring wrong and it can take a finger off or send the door crashing down off balance.
What a homeowner in Bethlehem can reasonably do themselves is the groundwork: clear the garage, measure the rough opening width and height, and decide ahead of time whether they want a single wide door or want the opening narrowed for a smaller one. Past that, we'd rather you call before you buy a door off a shelf that doesn't fit a 1960 opening - sizing mismatches are the single most common reason we get called back to redo someone else's install. If your opening is standard and square, the job itself isn't exotic. If it's not, that's exactly the part not worth doing solo.