In beach volleyball, when you're digging, typically your blocker is up. You want to space yourself around your blocker. They're covering a certain area of the court and you're covering the other area of the court. You want to have your feet evenly spaced apart and you want to rise as if on a spring, with your arms out in front of you, like this. It's similar to passing and setting.
Sometimes you have to dig with your hands. This is legal as long as the ball is hard driven. If the ball is not hard driven, if it's an easy pass or a free ball, you can still overhand dig but your hands have to be together. It's important to adjust based on where the hitter is facing, but not to move too early. If you start to take a step to the wrong direction, it's unlikely that you'll be able to get back in position. So the best advice is to wait and watch your hitter.
Sometimes you only have a chance to dig with one arm. This is fine as long as you use the correct arm. If the ball's going to your left, use your left arm. If the ball's going to the right, use your right arm. Right-handers tend to try to use their right arm, regardless of which side the ball is on.
When you're digging, you don't want to dig the ball too far off the net or too close to the net. Some happy medium, five to ten feet off the net for your setter to set the ball for you. You want to give the setter time to get to the ball, so you don't want to dig too low so that they can't get there. Also, you don't want to dig it too high, so that they have trouble setting it. And that's how you dig in beach volleyball.