NEVER adjust the dial ring when the doors are closed. This way you will force the internal mechanism, and the doors will block.
SENSITIVE SKINS - LIGHT BEARDS
Use the lower positions, from 1 to 3
AVERAGE SKINS - MEDIUM BEARDS
Use the medium positions, from 3 to 5
AGGRESSIVE SHAVE - TOUGH BEARDS
Use the highest positions, from 5 to 9
If you want to clean or rinse the blade after shaving, you can twist the handle, opening the door a little, not much. This way the blade do not goes outside, and you can rinse the blade with some water under the tap, without touching the blade. Then dry the safety razor carefully with a towel or with a soft paper, and twist the handle, to block the doors and lock blade into razor.
Remember that you will have to lubricate your safety razor sometimes, take a look to this article, HOW TO LUBRICATE YOUR SAFETY RAZOR
For more information, about cleaning your safety razor, take a look to this article, HOW TO CLEAN YOUR SAFETY RAZOR