Always start with the bar on the floor. Pulling from the safety pins is a Rack Pull. Deadlifting top down is a Romanian Deadlift. With conventional DEADlifts the bar must always start on the floor. Here's how to Deadlift in 5 easy steps:

Stand with the bar above the center of your feet - your stance should be a bit more narrow than shoulder-width to give your arms room.
Grab the bar overhand so your arms are vertical to the floor - if your hamstrings are tight, do Squat 2 stands to boost your hip flexibility.
Bend through your knees until your shins hit the bar which must remain above the middle of your feet. Shoulder-blades directly over the bar.
Lift your chest but don't squeeze your shoulder-blades like on Squats. Just put your shoulders back & down, head inline with rest of your spine.
Pull - keep the bar close to your body, roll it over your knees and thighs until your hips and knees are locked. Do not lean back at the top.