Here is a great video tutorial for you- https://www.youtube.com/watch?v=deS96zGrjiY
You can purchase concrete patch in a bag, add water and put it over top of the bad areas. First, brush on a concrete bonding agent so that the new concrete adheres to the old.
This product works great: https://amzn.to/2Ikssv7
Thank you. I really appreciate your assistance.