This lesson is about:

• Greek mythology, i.e. Greek story-telling
• the great story-teller of all times, Homer
• Odyseus, the hero of one of Homer's books (1st part of one of his adventures)
• Usage:
  • Reflexive pronouns: we do it to ourselves, reflect upon ourselves
  • 3rd declension to perfect our understanding of the various disguises nouns take to baffle lesser mortals

Don't let that frighten you, Greek in this respect is much easier than Latin, and much, much easier than Russian. And we've been using these forms for a long time already.

1. When a new word is introduced, it is always presented with

the article to show masculine, feminine or neuter
the base form (nominative)
the genitive case form (whose?)
 

2. Once the genitive case form is known, all the other forms are easy to deduce

So don't worry, relax and you'll see that the 3rd declension is actually easier than the first two.
 

The only real difficulty is stress, accentuation. Which is not all that terrible either, if you make a point of practicing aloud, placing the stress where the written accent in your book tells you to. Once your ear knows it is:
τοῦ παιδός but τὸν παῖδα  that problem stops being one.
But you only learn accentuation by ear, by saying words out loud, by listening. Your eyes alone won't tell you, unless you've got a photographic memory for meaningless detail. Because accent marks are 99% meaningless, unless you use the language orally. And remembering meaningless bits of information is a waste of memory.
I can't repeat myself often enough: in languages, sounds and stress, or pitch, are to be uttered and heard, not merely seen.