Shoutbox

I would like to know how to read a string in a message being send to me.
So like when i someone sends me:

!blabla number one:number two

then i would like to get what is between '!blabla ' and the ':' in lets say the var called 'one'.
and i want to have everything thats behind the ':' in a var called 'two'.

any chances that somebody can tell me this?