How do i properly dye my hair w/ bleach?

Well, im wanting to dye my hair a flourescent purple but my hair is dark brown I dont really know how to use bleach.

How do I use bleach?
Do I have to water it down?
Do I keep the bleach in when I dye my hair?
how long do I keep the bleach...

in?
Can you buy bleach from big supermarkets ie ASDA/Tesco? If so, How much?
If not, where can I purchase hair bleach?
Also. I was wondering, can you buy a pack of hairdye and put bleach on beforehand and then put the hairdye on?
Any tips?

Thanks in advance.

it really would be best if you get it profesionally bleached
so you dont fry your hair off
and so you can learn from them and do it yourself next time knowing what your doing
How do I use bleach?
usually get the powder and mix it with peroxide, read the instructions to see how much of each is needed, a level 20 peoxide will be best for ou because its not too strong
Do I have to water it down?
no you dont add water to bleach
Do I keep the bleach in when I dye my hair?
no
first you bleach your hair, then wash all the bleach out so your hair is a yellowy-blondish colour
dry it, then dye it, and then wash the dye out
how long do I keep the bleach in?
read the instructions, some say half an hour, some say no longer than 40 minutes, ect
and the less time its on, the less damage it will do to your hair
Can you buy bleach from big supermarkets ie ASDA/Tesco? If so, How much?
yes, expect to pay around $20 and get the powder and peroxide
If not, where can I purchase hair bleach?
at places like priceline
Also. I was wondering, can you buy a pack of hairdye and put bleach on beforehand and then put the hairdye on?
thats what your supposed to do
bleach, wash it out, dry hair, dye, wash it out, dry hair

and remember, bleach will ruin you hairs strength, health and shine

You can buy a hair dye that already includes bleach like a platnum blond hair dye. That's what I did when I dyed my hair blue. Then you just go to like hot topic and get the purple dye.

Yes, you can usually purchase it in ASDA/Tesco (: Hair peroxide is generally no more than £10. It'll say on the instructions how to use it properly. Yes, you can peroxide then put hairdye on - however, it's recommended that you don't dye your hair for two months after having dyed it the first time because it'll damage your hair. Peroxide bleach especially makes your hair very brittle and strawlike so dying it afterwards might not have very good results.

Thanks, That helped a lot. (:

Ok, never water bleach down all you use is the bleach and peroxide, for a dark brown I suggest 20vol, which lifts 3-4 shades, when it becomes ginger then you may wash it off, dry it and then apply your hair colour