how old are your players Tracey?  there are a number of ways to teach players to run into space and not hog the ball.  start with spreading the entire team down the court (if they are young just use the centre corridor for this exercise, and have them stand in the side corridors) in a zigzag layout with everyone in their basic positions.  and then have them take the ball up and down the court in order driving into the center corridor.

you can also play numbers games.  everyone has a number, and you can only throw in order of the number and then you have to find a new space.  you can then change the order to odd numbers or even numbers, or break the team into half and have defence.

the third way is to teach set plays. (ie C to WA to GS to GA who shoots), then everyone has a role, a location, and a known idea what to do.  this is good for getting them into basic idea of how to spread out, and where they should be.  

after a lot of calling out "spread out!" over a season, my team was finally starting to spread out, and be patient about letting others get the ball.  its a tough lesson for most, but the younger they are the more likely they will want to hog the ball.

hope this helps.