Has anybody idea how you can avoid seeing bad dreams? I have nightmares nearly every night now days.

Sometimes it works if you empty all disturbing thoughts from your mind and concentrate on the good before bed. But because dreams often come from things buried so deep you're not even conscious of, this doesn't always work.
Something to try anyhow.

Works in reverse too sometimes if you want to dream about something specific.

Most dreams are the sub-conscious at work interpreting feelings about self and the world. This is my favourite site when it comes to dream interpretation.