"I don't like this wine."
Translation:No me gusta este vino.
"Mi" literally means "my", so it would only be used when you're expressing possession of something. For example, "Es mi mochila" -> It is MY backpack. Or, "Ella es mi amiga" -> She is MY friend.
On the other hand, "me" is reflexive. It can be used with the verb gustar to indicate something is pleasing to you. So, if you say "Me gusta vino" it's really like saying "Wine is pleasing to ME" in English. "Me" can also be used in reflexive verbs where you express doing something to yourself. For example, You can say "Voy a ducharme" --> I'm going to shower MYSELF.
I hope this makes sense!
I'm confused why it is "me gusta" and not "me gusto". It says that I used the "yo form instead of the el/ella/usted form".... but why shouldn't I use the "yo form" since I'm talking about myself?
Esto is for it is este/esta is for this therefore este for male and esta for female. It's confusing sometimes
When a verb requires an object pronoun (direct or indirect), any negatives (no, nunca, etc) must precede the object pronoun. See https://www.spanishdict.com/guide/direct-and-indirect-object-pronouns-in-spanish