Sentence

[Aysok]

Oe lu nítxan nitram nume Na'vi
Correct me because I think nitram is wrong and Im not sure how to put to.

[Kemaweyan]

I think you want to say

Oer prrte' lu nìtxan fwa nume lì'fyati leNa'vi.

[Hawnuyu atxen]

I think you want to say

Oer prrte' lu nìtxan fwa nume lì'fyati leNa'vi.

Or simplier:
Oe 'efu nitram nìtxan talun oe nerume lì'fya lena'vi.
I feel very happy, because i'm learning na'vi.

[Aysok]

Why was the r added to oe? Thanks
Edit: I need help learning prefixes, infixes, and suffixes in Na'vi so next time you guys should explain what was done to make the sentance correct. (not just on me on everybody)

[Payä Tìrol]

Oer(u) is the Dative of Oe

Oer prrte' lu would be "(It) is pleasing to me"

[Kemaweyan]

Or simplier:
Oe 'efu nitram nìtxan talun oe nerume lì'fya lena'vi.
I feel very happy, because i'm learning na'vi.

So.. the second "oe" you can drop... And lì'fya should be in accusative case: nerume lì'fyati And seems to me that infix -er- isn't required here, because "I'm happy because I learn language", not "I'm happy because I'm learning language (right now)". Although maybe your way with -er- also is possible...

I think better to say

Oe 'efu nitram nìtxan furia nume lì'fyati leNa'vi.

[Payä Tìrol]

explain what was done to make the sentance correct

You wanted to say "I am very happy to learn Na'vi", right?

-Na'vi doesn't generally say "I am happy." you either use:
oeru prrte' lu "It is pleasing to me"
oeru teya si"fills me (with joy)"
oe 'efu ____ "I feel _____" This can be used for a wide variety of emotions and "states" like hunger, etc.

-When you say just Na'vi, it means "the People".
Instead, you say lì'fya leNa'vi "the Na'vi language", where leNa'vi is just Na'vi being used as an adjective.

-I couldn't tell you how "to be (adjective) to (verb)" works in English, but you can't translate that literally into Na'vi, so, we use the construction I pointed out at the top:
____ oeru prrte' lu
Except, the thing that's pleasing to you isn't a single word, it's a clause, so we use a sort of placeholder Fì'u a which is contracted to Fwa to describe it.
Oer prrte' lu nìtxan fwa nume lì'fyati leNa'vi.
Literally: It is very pleasing to me, that-is-this-thing-(I learn the Na'vi language)
or: That I learn Na'vi is very pleasing to me.

I need help learning prefixes, infixes, and suffixes in Na'vi

Do you have something specific in mind? This is quite a wide question.