What do I need to replace the strings on an acoustic guitar?

I've been using the "locking" method in the link Russell posted for over 30 years. Using that method, you don't need to wrap the string more than once around the post. http://www.fretnotguitarrepair.com/repair/acoustic... The example in the photo shows 2 winds, but since the string tightens on itself, you can get away with very little string wrapped around the post. Less winds are better because it takes the string less time to settle in. This also means you don't have to turn the peg very much, which pretty much makes a crank become more trouble than it's worth.

So to answer your question, you don't need a string crank to change strings. Even if you wrap the string around the post a bunch of times, you still don't need a crank. You will, however, need to turn the peg a lot more by hand.

Best-case scenario, you don't absolutely HAVE to have anything but the replacement strings. Something to clip the ends off when you're done will make for a neat job, though. If the bridge pins cannot be pulled out by hand, you can either get a pin puller (as pointed out earlier, string cranks often have one built in) or reach inside the soundhole and pop the pins out from the inside, using a random object such as a coin to apply pressure. Do not use pliers on the bridge pins. String cranks can be a great time saver, especially when restringing multiple guitars, but are not at all necessary.

this is a really good tutorial on how to change strings

http://www.fretnotguitarrepair.com/repair/acoustic...

I used this method to restring my double neck guitar, since the string crank couldn't be used on the inner tuning keys.

All you need is a few winds.

A string crank is very cheap and very useful, indeed, though. They didn't come out until the mid to late 70's and when they did, I was a real happy camper!!

I take it you mean a steel-string guitar. No, you don't need a string-winder but the job is much easier with one and they only cost a few bucks. Most of them include a bridge-pin lifter.

Here's an excellent article with photos to show you exactly how to do it right:

http://www.frets.com/FretsPages/Musician/Guitar/Se...

Just new strings and the knowledge of how to install them.

There are various methods, and you do not include a photo, so your best choice is to go to a Supply store and buy what you need.

you can do it alne just loosen the strings, but you have to make sure they are the right strings.