gas regulator question (first time gas user)

[owas]

so ive finaly gotten some gas to use but im unsure of how to use the regulator, when i turn the open valve on the gas bottle theres alot of air comming out of the top hole on the regulator, what is that?
also how do i adjust the flow rate etc

i have attached an image to show the one i have

 

[Paul.]

I've rotated the picture,
If you have gas leaking out of the hole in that hexagon nut on the top then the regulator is broken internally, that is a safety vent to prevent full cylinder pressure being sent to the welder.
For a quick guide on setting up a gas cylinder, its covered in the tutorial pages here
http://www.mig-welding.co.uk/wiki/Setting_up_the_gas