北海道の素晴らしさを世界の人々にシェアしたいって英語でなんて言うの？

Both of these answers are a good way of telling everyone was a great place Hokkaido is and that you think people should have a look at it.
It can be difficult on social media to get people interested in what you share, so one of these answers would be very good, with some photographs of Hokkaido too and it will entice people to take a look.

This sentence describes what you would like to use your profile for, which is how great Hokkaido is. You can use the word "profile" to describe your social media account.

I hope that this helps! :)

When you want to explain that you want to share the greatness of Hakkaido with people around the world, then you can say:
-I love Hakkaido. I think people around the world need to experience its greatness.
-I want to share the greatness of Hakkaido with people around the world

"I want to spread the greatness of Hokkaido to people all around the world!"
To 'spread' around means to share around.

When you want to write about sharing sharing your greatness of Hokkaido any of the above would be good examples to use.

You love Hokkaido. You want to write something like "I want to share the greatness of Hokkaido to people around the world" on your social media account profile. Well, there are a couple of alternative suggestions above.