You've already got a good idea of the topics you'll need to cover in your presentation: the main characteristics of an oral tradition, how these characteristics appear in Homer's works, and how the Greek oral tradition differs from the oral traditions of other countries. How much detail you want to...
You've already got a good idea of the topics you'll need to cover in your presentation: the main characteristics of an oral tradition, how these characteristics appear in Homer's works, and how the Greek oral tradition differs from the oral traditions of other countries. How much detail you want to provide on each of these topics depends on how long your presentation is meant to be. For the purpose of this answer, I'll assume you have about 15-20 minutes, so you should provide a succinct overview of each topic, highlighted with a few examples.
Start with the characteristics of oral traditions. As the term implies, these are spoken, rather than written, means of transmitting information. They were essential to pre-literate societies, where they served the function of passing myths, legends, biographies, and laws down through generations, helping to establish institutions and mores and to strengthen social identity. They were not merely tools used by people of the past, either, for oral traditions still exist all over the world, according to the Encyclopedia Britannica:
[...numerous] studies—conducted on six continents—have illustrated that oral tradition remains the dominant mode of communication in the 21st century, despite increasing rates of literacy.
The term "oral tradition" is a blanket which covers myriad types of information, including poetry, songs, storytelling, laws, rituals, social customs, and genealogy. The people who transmit this information usually hold a formal place in their societies, acknowledging their importance to maintaining the social fabric. They often spend years learning their material, which they memorize through use of complex mnemonic devices, like specific rhythms to their speech, and repeated use of certain words or phrases. These devices work a bit like the refrain in a song: the verses are different, but the song always returns to the refrain. The refrain is a "landmark" in the song which makes it easier to remember the bits that change between refrains. Likewise, the mnemonic devices used in oral traditions enable the speakers to return to a kind of "refrain" in their speech, which anchors the content of the speech to a pattern that is more easily remembered.
It's the use of these sorts of mnemonic devices throughout the Iliad and the Odyssey which led scholars to conclude that Homer's epic poems were originally transmitted orally, perhaps for centuries before they were ever written down. The key evidence scholars point to is Homer's extensive use of epithets throughout each poem, for example "swift-footed Achilles," "gray-eyed Athena," or "Hector, breaker of horses." Epithets are used for places as well as people: "Tiryns of the mighty walls," "Mycenae, rich in gold," and the famous "wine-dark sea." There are also stock phrases, such as "When Dawn spread out her finger tips of rose," and "‘Son of Laërtês and the gods of old, / Odysseus, master mariner and soldier." The repetition provides a framework the speaker can build the story upon. It allows the speaker some flexibility in the verses between repeated lines, while also ensuring he doesn't stray too far from the content he has memorized.
Homer's Iliad and Odyssey are both written in a poetic meter called dactylic hexameter, and his use of repetition often helps his words to conform to this meter. Maintaining a strict rhythm in speech is a technique frequently used by transmitters of oral traditions. Like the repetition of words and phrases, the repetition of specific sounds helps anchor the speaker in their speech, enabling them to memorize huge amounts of information.
Once you've covered what constitutes an oral tradition and touched on the evidence of oral transmission in Homer's works, you can consider how the Greek oral tradition differs from the traditions of other countries. Homer lived during the Greek Dark Ages (approximately 1200 to 800 B.C.). The Mycenaean and Minoan civilizations of the ancient Aegean had collapsed, and only people like Homer could preserve the traces of culture from that era. Homer was mainly concerned with passing down history and legend from the vanished civilizations, as evidence of his people's glorious past. Many oral traditions are concerned with genealogy, tracing family lineages back through generations to establish and confirm the social hierarchy. Among Native Americans, Pueblo Indian storytellers pass on the collected myths and legends of their particular pueblos. West African griots are storytellers, singers, and general repositories of cultural knowledge. Many pre-literate societies used, and still use, oral traditions to record their laws. Australian Aboriginal tribes use songs about the land to essentially create an oral "map" of the country which they can use to navigate between landmarks.
There are many articles online discussing the different oral traditions around the world, so include a few examples of these in your presentation to compare and contrast to Homer's particular methods. This should help you wrap up your presentation by referring back to Homer's works in the broader context of global oral traditions.