I do it myself and this is what I use.

http://www.lorealparisusa.com/_us/_en/default.aspx#page=top{nav|media:_blank|overlay:_bl ank|diagnostic|main:brandpage:couleurexperte|userd ata//d+d//}

I'm not sure how to hyperlink it so you can copy and paste to get there. I do have short hair with kind of a messy style so I have some room for mistakes. If you have medium or long hair I would recommend going to a salon. JMHO