Step by step:

1. Get powder bleach (comes in little packets or big tubs). Get a lot.
2. Get developer (30 or 40)
3. Get toner.
4. Get dye.
5. Bleach. Depending on how dark your hair is, it may take a while. I have dark dark brown hair and it takes at least two bleachings (after the first one it’s usually a hideous orange). When rinsing out the bleach, shampoo and condition. Generally they say to wait one day between bleaching, but that might take a while with how light you’re going, so I’ll say do one in the morning, one at night, repeat until satisfactory. Once your hair is super light..
6. Tone. Mix the toner with the developer, and follow directions.
7. Dye. I don’t have a ratio of dye-to-conditioner, but take your conditioner, put it in a clear bottle, and start adding a little dye  at a time, shaking and stirring to mix it up. You’ll want it at least a shade or two DARKER than what you want your hair. The initial dye you might want to take some of the dyed conditioner out and add a bit of extra dye, then let that sit in your hair maybe 10-15 minutes (because you want it light).
8. Don’t shampoo it out (unless it’s too dark). From now on, use your dyed conditioner as your conditioner, leaving it in a few minutes in the shower.
9. If your conditioner makes your hair too dark, add more conditioner to dilute it (which is why you’re putting it in a separate bottle).

(I’ve dyed my hair every single possible color, including white (which lasted about three days because it looked terrible on me), and could bleach my hair in my sleep.. I don’t follow my own bleaching advice though because when I did white I bleached 6x for an hour each time in one day. My scalp burned for three days. I didn’t even need the last bleach or two either… BUT YEAH. Immortal hair. Do as I say, not as I do.)