[Chemistry] Represent skeletal formula as structural formula / semi-structural formula?

Good day, I need a precise explanation of how to represent a skeletal formula as a structural formula and also how to represent a skeletal formula as a semi-structural formula. I'm very much looking forward to your detailed explanations, preferably step-by-step, with graphics if possible. I would like to understand this using the example of…

Hey, how do I recognize a peroxide based on the reaction equation?

Hey, we were supposed to determine the oxidation numbers of certain molecules in a reaction equation. We learned that the oxygen atoms in a compound have an oxidation number of -2. The exception to this is a peroxide, where the oxygen atom would then have an oxidation number of -1. My question now is, how…