What does compound and complex grammar mean in a sentence?

A compound sentence says two different things. For example, Come to my house at 5:00 and bring a salad. A complex sentence has a complicated structure. For example, it was only after hearing the crash in the other room that Henry realized how careless he had been in assuming, simply because he had not seen anyone else, that he was the only person in the house which he had considered to be his castle, until that evening when fateful events overtook him, as fateful events will do.