This is a link to your manual, DX8 on pages 23 and 24 it explains how to adjust the expo. Adding expo will make the center stick position "softer" meaning when you move the stick in the middle the helicopter / swash will be less responsive allowing you to hover alot easier without the helicopter moving around alot. One thing to keep in mind though is the "softness" is only around the center stick positions the further the stick is moved to the end of its throw the less the expo will affect the movement and it will be more lively out there. If learning to fly / hover there should not be a reason to have the sticks out towards the edges anyway, make small corrections to keep a solid hover. If you make too quick or too big of stick movements you may find yourself chasing it around. Keep the stick inputs small!
Another useful way of taming the birds is to slow down its head speed. This is probably what you should do first then if you want to play with the expo settings go ahead and do that. Obviously you can only slow down the head speed so much, if it is still too lively then add the expo. The head speed can be adjusted in the throttle curve settings on page 26. My 130 has an upgraded motor in it, I have not flown it with the stock motor so Im not sure how much power it has to be able to tell you how slow to make it. For normal mode your curve probably looks like an arch, the left side is at 0, the right is at 100, for me this mode / curve is basically for spooling up, lift off and landing. As soon as I have the bird in the air I flip it into Idle up / Idle 1, this way it is a habbit and I wont forget it is still in normal, try to go inverted causing a crash due to no negative lift. If you flip to Idle 1 for hovering, make your throttle curve linear, meaning the same value all the way across and try setting it at 70, then you can set Idle 2 at 75 or 80 all the way across. With these linear settings the motor will keep the same speed no matter where your collective / throttle stick are in their travel. Keep in mind Idle 1 & 2 problably have negative collective if you have the pitch settings set to the recommended settings for the DX8.
Let me know if this helps or if you have any questions.