Just adding to what allhallows wrote: CBT stands for cognitive behavioural therapy, the cognition being awareness of how your thoughts & feelings influence behaviour. The driving force of CBT is "Feelings follow thoughts, and actions follow feelings." This can be illustrated by thinking about a luscious meal: it can make you feel hungry, so then you get the urge to eat.
Most people, if they're on a diet for example, would go through that process without realising it. Then they would fight the urge to eat - which is a lot harder than it would be if you stopped the process earlier on. CBT teaches us how to become aware of our thought-to-feeling processes. This gives us a choice on whether to follow through with the action. Ideally, we learn to recognise it at the thought stage. By changing the thought, we change the process and get a different outcome.
It works brilliantly for a lot of apparently serious problems: most of us are unaware of what we're doing until we learn to understand it. I'm grateful to CBT because it taught me how to 'hear' my inner critic. In my case, CBT couldn't fix the fact that I have such a vicious inner critic - that required deeper psychological work. All the same, it helped me tremendously with several everyday issues. It also prepared me for the heavy psychodynamic work that followed.
You do need to have patience with yourself. If you end up finding a wise & expereinced counsellor, that will help you move along but I'd still recommend the book and the mood gym for starters.
Good luck :)