Hiya!
Did you use bleach or just a normal tube of tint?
If you used bleach then the problem is that you didn't leave the bleach on long enough. When the bleach has been applied, the bleach strips out colour from the hair one by one. So that it lightens the hair. Apply the bleach again. And make sure you keep a wet piece of cotton wool with you to remove the colour a little from different parts of the head to see if you've got the results you wanted.
The most common problem of bleaching hair is the orange bit. When it turns orange, people get alarmed and rinse it off! The hair goes through a orange state, it's normal. Because you had brown hair, brown will be stripped out, then orange, then you're left with blonde. So when you've got the desired result, rinse off asap.
