I can speak two languages;: Japanese and English.

Two connected thoughts.

I don't think that my English skills isare great so far, but I think I should have athe confidence properly in order to improve my English skills.

Skills (plural) needs the plural of "to be" (are).
Sometimes, using less words gets your point across more easily,

Studying is fun for me, some people feel creepy to memight find me creepy for that though.

Not sure if this is what you were trying to express?

I don't think my English skills isare great so far, but I think I should have aneed confidence properly in order to improve my English skills.

Studying is fun for me, some people feelact creepy toily around me though.

Not sure how studying and creepy people can come together haha. Do they intimidate/overwhelm/scare you? Maybe look for alternate adjectives!

I don't think my English skills isare great so far, but I think I should have abe confidence properlyt in order to improve my English skills.

Because "skills" are plural, you need to use are not is. Usually, I don't say "have confidence". Instead, use "be confident," and properly doesn't apply here because it usually refers to a verb.

Studying is fun for me, some peoplesubjects feel creepscary to me though.

Not sure what you were trying to say here, because "some people feel creepy to me" general means that other people are weird or dangerous in your opinion. Saying that some topics you study are "scary" or "daunting" makes more sense. Don't use creepy in this context, as it has a much different meaning.

I can speak two languages;: Japanese and English.

The semi-colon is used to show that two related thoughts are connected. In this case, you're telling the reader that you can read two languages and then expounding on which two languages those are.

I don't think my English skills isare that great so far, but I think I should have aproper confidence properly in order to improve my English skills.

It's a little unclear what the writer is trying to convey. It's clear that they are commenting on their English language skills in the first half of the sentence. If the second half of the sentence is meant to convey that they must have confidence in their skills in order to continue to learn the language, then "but I think I should have proper confidence in order to improve my English skills." is correct, although in American English, it's rarer to see the use of "proper" as an adjective when compared to British English.

Studying is fun for me, but some people feel creepy to me though.

If this is conversational English. I would replace the comma with a "but". If this is academic English, I would consider the use of a semicolon because they are related but distinct ideas. The "creepy" idea is correct as written if the writer is trying to say that they find some people creepy (when they're studying).

I can speak two languages;: Japanese and English.

I don't think that my English skills isare great so far, but I think I should have athe confidence properly in order to improve my English skillsto improve.

Studying is fun for me, some people feel creepy to me though.

I can speak two languages;: Japanese and English.

So far, I don't think my English skills is great so farare that good, but I think I should have amore confidence properly in order to improve my English skillsit.

Rephrased for slightly better flow.

Studying is fun for me, but some people make me feel creepy to me though.

I can speak two languages;: Japanese and English.

The semicolon (;) is used when joining two related sentences together. See the following site for more information: https://www.merriam-webster.com/grammar/a-guide-to-using-semicolons
Here the colon (:) is more appropriate since you are introducing a list of items.

I don't think my English skills isare great so far, but I think I should have a confidence properly in order to improve my English skills.

Since "skills" is plural, you should use "are" with it.
Reworded the second half to be more natural.

Studying is fun for me, but some people feel creepy to me thoughI come across feel creepy.

"to me" isn't incorrect here, but if you've already included "for me" it's best not to repeat it.
The second half could do with something extra to indicate who these people are. I'm not entirely sure if this is what you intended to say, but it is my best guess.