This takes a lot of work and online might not cut it. I'll give you an example: I have very scary lucid dreams with sleep paralysis. Every time I fell asleep (naps included) I would say: I want to dream about 3rd grade and re-visit my old class and be in the room etc. I would try to imagine the room, the kids, the teacher. It took TWO WEEKS of doing that every day until I finally dreamt about 3rd grade. I would NOT say "I don't want to lucid dream" I would merely focus on what I wanted to dream about.
Getting over past issues is hard, but not impossible. Basically, you have to get to a point where you're OK with moving on. Not OK with the issue, OK with moving on! It happened, it's over, whatever it is it can't hurt you anymore. It may help to focus on something else or maybe you need to work it out - really let yourself process and feel it. Write it down, but go slow. Depends on how traumatic it is, but go slow, go easy on yourself. Ignoring the problem doesn't work because it manifests in other ways: Depression, pain, anxiety, nightmares, etc.
Starting living in the present. Every time you feel yourself going back to the past, stop yourself, take a slow deep breath, and think about your body, what it feels like. Find a place in your body with no pain and focus on that - even if it's the top of your foot or something. Live in the now more and the past moves further away.