Hello! I don't know what I'm to dodoing

Hello to you who arewhoever is reading this .¶
My name is Sabrinna, and I wish to speaking fluent English fluent.

Hello! I don't know what I'm to dodoing.

Hello to you who arewhoever is reading this. ¶
My name is Sabrinna and I wish to speaking fluent English fluent.

MY GUESS: Hello! I don't know what I'm to should do.

Hello to you who are read this all readers!¶
My name is Sabrinna and I wish to speaking English fluently.

Hello! I don't know what I'm to should do

"What I'm to do" can work, but it's a little poetic, and I'm not sure if that's what you wanted here.

Hello to you who are reading this ¶
My name is Sabrinna and I wish to speaking English fluently

When saying that someone IS doing an action, we use the progressive tense of a verb ("_____ing")
"I am reading" "You are reading" "She is reading" "To whoever is reading"

Because we are describing an action, "to speak", and not a noun, it is better to use an adverb (most of the time they end in "ly"). This isn't a super big issue, but it can make your English sound much more natural.
For example: "I am quick. I walk quickly to the store." "I" is a noun, so it is described with an adjective: "quick". But "walk" is a verb, so it is described with an adverb: "quickly".

If you instead want to describe the noun "English" as "fluent", we'd say: "...and I wish to speak fluent English".

Hello! I don't know what I'm to do

Your sentence is grammatical, but alternatively: "I don't know what I'm supposed to do".

Hello to you who are reading this .¶
My name is Sabrinna and I wish to speaking English fluently.