As has been already noted, the official warning count does not show up on your profile if you do not have any official warnings.
As for the reasons for official warnings themselves (Marking's question) see the lovely
Forum Rules that we have in place to explain all of these things:
RSBANDB Rules - read them again wrote:
Official Warning
A private message will be sent to you from a mod or admin warning you of your behaviour. Your warning count will also increase by one.
Basically, when an official warning is given to you, a PM will also be sent informing you of this and what you did. You will always be in full knowledge of what you did wrong.
Not to be a totally annoying Moderator, but actually reading through the rules a couple times (as well as using common sense) will usually help you in what you should or should not do in the first place.
And as nothing more really needs to be said, I'll be locking this.