Been there done that.  So you know what is coming up,
I have pre-posted the follow-on questions for you:

 > Could you please explain [how to put a lens together again]

And the ever popular:

 > I have this part left over, it looks like a half-moon with a
 > bite out of the outside ... is it important?

 > I can't find the thing that goes from the aperture ring to
 > this little notch in the ... do I really need it?

There are already web sites to help you:

http://www.hermes.net.au/bayling/repair.html

===========

Don't mean to be all that sarcastic, but for most of us
the training is OJT: "On The Job".  You just start taking things
apart and putting them back together again until you don't
have any parts left over and everything seems to work.

There are sites, though not many, that do offer help:
http://www.kyphoto.com/classics/forum/messages/board-topics.html

If you have one, or can get one, use a broken throw-away lens to
practice on.

Here is what I have learned in general practices:

As you take the lens apart:
1) Take lots of notes.  Make sketches.
2) Take more notes.  More sketches.
3) A video will help, because you didn't
   take enough notes or make enough sketches
These are _very_ important if you are working on a shutter.

Work on a white fuzzy towel so that when something sproings
or drops it doesn't roll away.

Vacuum the floor before you start working to make it
easier to find parts that sproinged and rolled away.
A magnet can be a good thing to have for 'sweeping' the
floor to find lost parts.

Use only the best quality tools you can find/but/beg/borrow/steal.
http://medfmt.8k.com/mf/repairtools.html

There will be a tool or two you don't have.  A small grinding
wheel or dremel tool can help make the right size screw driver
or can be used to make a special spanner wrench.

Use _exactly_ the right size screwdriver.  You will not have
the right size screw driver so get used to grinding down
screw drivers to make an exact fit.  Push in hard when
unscrewing so the screw driver doesn't slip.

Don't use a lot of turning force on screw head.  If the head begins
to go bad stop work and give the whole thing to a repair shop.
To continue working on a bad screw head without practice [or even
with practice] will make things worse.

Sometimes a drop of WD-40 and a 48 hour rest in someplace
warm will let a screw loosen.  It won't hurt to put a drop
of WD-40 [with a toothpick] on all the screw threads
and ring threads you can see and let the lens rest for
a few days.  Clean off the WD-40 with Ronsonol before
putting things back together again.  _NEVER_ put screws
back on with oil on the threads: you can then exert too
much force and strip the threads.

To work on a lens you will need a good 'spanner wrench'.
http://www.skgrimes.com/span/index.htm
You probably don't have one.  You can make one from an old
cheap metal vernier caliper by grinding down the tips.

And on, and on ...

 The only way to do it is to start doing it...