Start first by describing the event associated with the negative feeling state. Describe it objectively without putting any spin on it - just the facts of what happened.
Now describe the feelings you are having about the event. Try to be as specific as you can. For example, if you are angry ask yourself if it is Hurt-Angry or Frustrated-Anger. It is perfectly okay to list a set of different feelings if you are having them.
Now begin to write down the thoughts you are having about the event. Try to have this step be a "stream of consciousness." Try hard to not edit or censor yourself as if someone is looking over your shoulders. It is also okay to have thoughts start out in one direction and then link up and wind up in a completely different direction. That's just how our thought patterns work. Continue to write in a stream of consciousness fashion until you feel you have said all you have to say about the event.
Now try to write thoughts about the event but try to express them without the cognitive distortions. This last step is not "positive thinking" to replace "negative thinking." This steps seeks to replace distorted thinking with thoughts more in alignment with reality without the distorted filters. Don't just change the content. Change the filter. For example, don't replace negative fortune telling with positive fortune telling. Avoid fortune telling at all.