Congrats on your first spindle. Spinning is a lot of fun. To answer your questions as best I can here:
- Pre-drafting is where you take a strip of roving (for a beginner you might want to start with a strip of roving no bigger around than your thumb) and separate the fibers. First you'll want to determine your wool's staple length. Grab the end of your bat or rolag (batts look like little flat, wide tufts of fiber. Rolags are in a "tube" shape) and give the fiber a gentle tug until it separates from your batt or rolag. Measure it in inches. That is your staple length. This will help you with both pre-drafting and while you're spinning, but I'll get to that.
Okay, so let's say you're working with a wool batt that has a staple length of five inches. Gently pinch the end of your strip of roving that you pulled off your main body of fiber between your tumb and index finger of your right hand. Now move about four to six inches up and pinch the fibers there with your left hand. Slowly and gently pull your hands apart just until you feel the fibers begin to slip past one another. Move your right hand up to just above where your left hand just was and your left hand accordingly and do it again. Don't pull the fibers too far apart. That will cause your strip of roving to break with you go to spin them. You just want to give it a slow, gentle tug until the fibers slip. Do this all the way up your length of roving. You'll notice it got a lot longer and it looks much easier to work with.
You can't ply from one single. If you really want to ply what you have now, you could try winding about half of the yarn you spun off the shaft of your spindle onto a toilet paper tub, cut it and then wind the rest off onto another toilet paper tube.
To ply you're simply going to grab the ends of your two singles, tie the ends together around the shaft of your spindle. Loop the two strands under the hook of your spindle and spin in the opposite direction you spun the spindle for spinning the yarn. Typically you put what's called an S twist in your singles by spinning the spindle counter-clockwise. When you ply you put what's called a Z twist into the yarn by spinning the spindle clockwise. By spinning the spindle in the opposite direction for plying you prevent the twist from leaving your spun singles.
Make sure as you're plying that you don't let the singles kink back on themselves. This will result in poorly spun spots.
Anyway, just continue to spin your plies together, letting the twist freely run up the strands and wind off onto the spindle when the strands gets too long to manage.
After you ply, you have to set the twist (otherwise your yarn will forever look like a pile of Ramen noodles, which also makes for difficult knitting). Using a Niddy Noddy or the backs of two chairs you need to make a hank, just like you find at the LYS. Make sure you don't make too short a hank. Your freshly spun yarn needs some length so that any spots that are too tightly spun can even out throughout the strand. Tie it together (there is a video on how to do this at iSpindle) and toss in a sink or basin filled with hot water. Let the hank soak for at least an hour. Try to resist the temptation to keep touching it. Just let it rest in the hot water. After some time has passed, grab it from the sink and gently squeeze the excess water out of it. Don't wring it out, which will cause it to felt. Then roll it up tightly in a towel to press out the remaining moisture. Then grab the end of your hank and give your yarn a few good whacks against the side of the tub, sink or a countertop. This is called "thwacking".
Hang dry with a towel underneath at least overnight. Do not weight the hank! Some older instructions call for putting a can of soup in the bottom loop of your hank. Don't do this. It will create unwanted tension at the bottom of your hank, thus weakening the fibers.
Once it's dry have fun with it.