I am having trouble with oxidation-reduction reactions and telling which substance is oxidized/reducing agent and which is reduced/oxidizing agent.

I am having trouble with oxidation-reduction reactions and telling which substance is oxidized/reducing agent and which is reduced/oxidizing agent. Also, I am having problems with balancing redox equations. Is there somewhere that I can maybe watch videos? Or can you give an example and explain?

Oxidation involves an increase in the oxidation number of an atom.Reduction occurs when the oxidation number of an atom decreases.According to this reaction , CO2 is reduced when it reacts with...