essentially it's a case of lining up the dots.
you want to be shooting the right kind of target at the right range... 10m targets like this
then it's a case of centering the target black dot in the centre of the foresight, which should be in the centre of the rearsight. The rearsight will be blurry, the main point of focus is the foresight.
Once they're all lined up, pull the trigger
If your rearsight is adjustable, play with it...smaller openings on the rearsight give better depth of field, enabling you to see the target against the foresight clearer, but too small a hole will tire your eyes.
The foresight normally has swapable elements to change it's diameter...this changes the ring of white thickness between the target and the foresight...4.0 is a good place to start...too thin and the optical effects will give you problems, too wide and it will be difficult to determine when it's central.
It takes a bit of practice to get somewhere in 10m, but it's highly addictive given a good attempt.