Introducing Myself

You can say "présentation", it is better.

Salut.

"Salut" is adapted for informal situations, here, "bonjour" is better.

Je ma'appelle Pelumi.

Je 'habite Lagos.

You must put an apostrophe because "je" ends with a vowel and "habite" begins with a vowel.

Je travaille à Ikoyi.

Here you must use "à" because you are indicated the place where you work.

Je suis Etudiant French'étudie le français avec Duolingo.

Au revior Aoir, à bientotôt.

Introducing MyselfPrésentation

A text or speech where you tell about yourself is called "une présentation" in French

Je ma'appelle Pelumi.

me+vowel => m'

Je 'habite (à) Lagos.

je+vowel => j'
(the <h> is unpronounced here so the word starts with a vowel)

Je travaille à Ikoyi.

All cities, villages, settlements etc require the preposition "à"
"habiter" tolerates a direct object (as above), but with "travailler" you have to add an adverbial phrase of place

Je suis Etudiant French'étudie le français avec/sur Duolingo.

Je suis étudiant(e) = I'm a student
J'étudie = I'm studying, I study

French = français
Language names are considered common nouns, so they're not capitalized and work with articles ("parler" being the big exception because you can say both "je parle LE français" and "je parle français")

Au revior Aoir, à bientoôt

"au" and then "revoir", literally, "(until) the moment we see each other again"