In short
A bodygraph is read in four steps: first the Type (there are only five), then the inner Authority, then the colored centers, and finally the Profile — two numbers like 1/3. You don't need to learn all 64 Gates right away; they come in handy later. To start using your chart, one evening is enough — for the Type and Authority.
What you're actually looking at
A bodygraph is a diagram of nine shapes connected by lines. The shapes are called centers, the lines between them are channels, and the numbers at the ends of the channels are Gates. Colored centers work all the time; white ones change depending on who is around you.
The colored columns to the left and right of the diagram are the positions of the planets. The left one (red) is the Design chart, meaning the unconscious: what works on its own and is more noticeable from the outside. The right one (black) is the Personality: what you know about yourself. A beginner doesn't have to figure out the columns.
Reading order: four steps
First — the Type. It tells you how your energy is built and by what rule to enter situations. There are only five Types, and this is the most useful knowledge in the whole chart.
Second — the inner Authority. The Type answers “how to enter”, the Authority answers “what to decide with”: body, time, voice or environment. This is what you'll use every day.
Third — which centers are colored. Defined centers are your constant; it doesn't depend on the company you keep. Open ones are the places where you amplify other people's energy and, over time, gain wisdom about it.
Fourth — the Profile, two numbers like 1/3 or 4/6. It's about your role among people: how you learn, how people find you, what they see in you before you notice it yourself.
What not to do right away
Don't try to learn all 64 Gates. They'll be useful, but later: first the Type and Authority, then the centers, and only then the details. A person who starts with the Gates usually drowns and quits.
Don't look for a verdict in the chart. A bodygraph doesn't tell you what to do for a living or whom to start a family with. It describes mechanics: where things come easily to you and where you spend energy resisting your own design.
Don't compare how much is colored. More defined centers doesn't mean a “better chart” — it means less flexibility and more consistency.
How to check that you understand it correctly
Take one decision you made in the last month and see whether it was made by your Strategy. If it was, recall how you felt afterward. If it wasn't, recall that too. The difference between those two feelings is the whole practice of Human Design; the rest is detail.