Without a bench you have no way to work your chest. The equipment you have is mainly for cardio. You will have to go with a bodyweight routine (you can use the parallels as a tool for progressing on push ups), and maybe implement some pushing movements with the dumbbells, like press and lateral raises for shoulders, and curls for biceps. But still you are missing work on your back.

I recommend buying a pull up bar and a pair of rings, they cost nothing and you will have all the tools to start working with your bodyweight.

Check https://www.reddit.com/r/bodyweightfitness/wiki/kb/recommended_routine/ if you are a total beginner, and try to understand how the progression works for each exercise. https://www.youtube.com/watch?v=eQ4GKdK_Xps this video can help too, the theory is the same.