Завтра я надену новую куртку.

• надеть (perfective) means “to put on” (clothes, shoes) on yourself or an object.
• одеть (perfective) means “to dress someone (else).”
In our sentence you’re talking about putting the jacket on yourself, so you use the verb надеть in its future‐perfective form я надену.

• надену is perfective – it emphasizes the completion of the action (“I will put on and be wearing it”).
• To speak of an ongoing or repeated action, use the imperfective future with буду + infinitive: Я буду надевать новую куртку (“I will be putting on a new jacket” or “I will repeatedly put on a new jacket”).

• новую куртку is in the accusative singular feminine because it’s the direct object of надену.
• Feminine adjectives ending in -ая change to -ую in the accusative: новая → новую.
• Feminine nouns ending in -а change to -у: куртка → куртку.

Russian word order is quite flexible:
• Завтра я надену новую куртку. (emphasis on “tomorrow”)
• Я завтра надену новую куртку. (neutral)
• Я надену новую куртку завтра. (emphasis on “jacket” or “tomorrow” depending on intonation)
You can move завтра for stylistic emphasis without changing the core meaning.

Subject pronouns are optional in Russian if the verb ending makes the subject clear.
You can say: Завтра надену новую куртку.
Here -у in надену already tells the listener it’s “I” (1st person singular).

Phonetic outline with stresses (caps = stressed syllable):
[ˈZAF-tra ya na-dʲɪ-ˈNU ˈNO-vu-yu ˈKUR-tku]
• ЗА́втра – stress on the first syllable.
• наде́ну – stress on the second syllable.
• но́вую, ку́ртку – stress on the first syllable of each word.