Started learning English newrecently

Recently is better since you're focusing on the time frame here.

I just decided to learn English newrecently.

I have studied English since I was in kindergarten, but that didn’t work very well.

Just sounds a bit more natural with the quantity-sounding term at the end.

I don’t usually use English because in my country people brarely talk in English.

In my high school, I was a member of ESS, where students study English, and I made some presentations andto show it off in public.

So I came here to become goodimprove at English.

improve is a more natural sounding word to use here.

In the future, I want to study abroad and work in the UK.

Most countries don't take "the", but the full name of the UK is "The United Kingdom of Great Britain and Northern Ireland" and the "the" is kept for abbreviations (like "the UK", "the United Kingdom") unless you just have the word "UK" on its own outside a sentence.

Or otherwielse.

I just decided to learn English newrecently.

I don’t usually use English because in my country people brarely talk in Englishspeak it.

In my high school, I was a member of ESS, where students study English, and I made some presentations and show ited them in public.

Started learning English newrecently

'Newly' is an adverb used before an adjective or past participle
Ex: 'Julia was newly married'
In your context, the word 'recently' would be better.
'Start' should be put in the past tense, since you've already started learning

I just decided to learn English newrecently.

'recently' vs. 'newly'

In my high school, I was a member of ESS, where students study English, and I made some presentations and showed it in public.

'show' should be past tense, because you are talking about the past.

However, my English has never improved.

Or otherwise.

So, I don't understand what this means. 'Or Otherwise' is a sentence fragment, and it can't be on it's own. You can add to it, or remove it, but it has to be a full sentence (subject, object, verb).