stop-loss using commsec

Does anyone know with Commsec when utilising internet for buys/sells is it possible to have stop losses set.
Have been in the market for quite a while, and ignorance on my part not sure whether it is possible or not with commsec, and has certainly bitten me at least once by not doing the aforementioned.

Also when setting stoplosss,one would assume that figure is constantly revised upwards/downwards dependant on s/p and what roughly is the general rule of thumb...is it 10% of s/p

Thanks for any replies and apologise if appears dumb point.