The rotations and change of positions during a match depends on whichever spot you play. If you play front row, your rotation is completely different than that of back row. If you are setter, you have your own individual rotation to go through. Also, there are many different rotation methods in volleyball. It depends on your coach and what he/she wants you to do. I would suggest asking the coach before, after, or during practice for extra help. If you're confused, then it's very likely that others on your team are confused.
Here's an example of a rotation, the one my team uses. When we're on defense, back row looks like a cup. Outside hitter (the one on the left side of the court) pulls back to back row. But she has to be sure to stay a little bit in front of the original back row players. Right back pulls up almost even with her, and the left and middle back stay behind them. Once the ball is served to our side and is hit back over, the outside hitter goes to her spot and the three backrow players are the only ones in back row. As for front row, it depends on what you're assigned as a position. There is a outside, middle, and weak hitter. Outside is far left, middle is middle, and weak is far right. No matter where you are at after you win a volley and rotate a spot, you always go back to your assigned spot once the ball is hit over the net. Then there is the setter. Wherever she's at depends on your coaches preference. So if I were you I would ask my coach for extra help. Whenever your team is on offense, it's pretty much the same except your outside hitter does not pull back and front row pulls off the net to wait for the setter to set one to someone.
It all depends on your coach and if your team can work as a team. So just make sure to work hard together, and never hesitate to ask your coach for help. Also, anytime you get a chance work with the volleyball. Any playtime is good playtime.
As for digging, you have to practice. If you've just started it will be tough but eventually you'll get the hang of it. Make sure to watch where the hitter/server is angled. Wherever her feet is pointed is most likely where she's going to hit it. Watch her entire arm, never take your eyes off of her. Stay in front of the ball, and make sure your entire body is there. Don't swing your arms EVER. Keep your arms out in front of you, squat down, and move your body up when the ball hits your arms. Make sure your body and your feet are facing your target, which would be your setter. And even though you have kneepads, you should never have to use them. Be quick on your feet and get there before the ball does. If that can't happen, then drop on your knees and stomach with your arms in front of you and just get the ball up in the air. Even if your setter can't get to it, someone else can. The main thing is to practice, practice, practice. Every little bit helps.
Good luck and have fun. Remember to ask for help.
I've been a volleyball player for five years.