Self introduction

Could you correct the following text and advise me?

'advise me' is fine here but it sounds a little formal, so I think it might be better to write "Could you correct the following text and give me your opinion?"

I am Japanese, and I turned to 19 years old last January.

I came to Australia to enjoy a working holiday.

I want to improve my English and experience lots of activities in Australia.

I think instead of "experience lots of activities" it would be more natural to write "take part in lots of activities" :)

I lived in an inland prefecture called Nara when I was in Japan, so I’m very interested in marine activities!

Writing "prefecture called Nara" sounds a bit more natural to me :)

I am quite a a bit of a stranger to Perth, (so) please lead guide me and tell me about this the city.

"A bit of a stranger to ~" is a useful phrase, you can use it when you're new to something.

Also, your use of 'lead' and 'this' are not wrong, but I put in the words I would use instead.

And I’m also interested in foreign cultures and histories, so please tell me about your country.

My English must be poor, especially, my pronunciation is awful.

I’d like to make it better in this collage.

Hmm, I'm not sure I understand the meaning here. Collage = コラージュ - is this the word you mean?

Finally, I wish hope we could can be good friends.