The blood test room is on level 1: follow the blue line from reception. It is a walk-in service on weekdays from 7:30 to 16:00 (sample); take a ticket at the door.
Some tests need you to fast, usually only water from the night before. The form from your doctor says so; if it does not, eat and drink as normal. Drinking water makes the test easier.
Results go to the doctor who asked for the test, usually within a week. They will contact you if anything needs to be discussed.