What should I think about when I meditate

When I first start meditating, I think only about my breath. I concentrate on the feelings of my body moving as air fills it and leaves it. Then I begin to imagine a healing, calming blue light that slowly fills my body with every inhale, and all the negative energy, thoughts or feelings leaving my body as a black smoke during every exhale. After settling into my practice for about a week or so, I begin to add in different elements such as gratitude, imaginary of what I want in my future, or sending good thoughts and love to those I care about. I always make sure to thank myself at the end of a practice; meditation can be tricky, especially in the beginning.

You shouldn’t think about anything just focus on your breath and flow of air in your nose and inhalation from your mouth and keep focusing on your feelings see what is coming and just notice them without any judgement or thinking why they are coming
Just see them and be aware of your presence

you should think about the place that gives you chill and peace, imagine you’re sitting at that place( just like i imagine peaceful mountain no noise), then relaxing your body accordingly. then take breath.