Hi,, I'm suji.

Hellow..
I've just left the site for long time.
and I start again.
Nice to meet you everybody.

so,,How are you?
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Hello,everyone.
I've left this website for long time,I start to visit it again right now.
Nice to  meet you.
How are you?

Hi,, I'm suji.

Hellow..  Hello
I've just left the site for long time. I've been gone from the site for a long time.
and I start again. I've just started again.
Nice to meet you everybody. Nice to meet you, everybody.

so,,How are you? How are you?

Practical notes: Although "Nice to meet you, everybody." is gramatically correct, normally, you probably would not use this here. You would probably say something like "I'm anxious to meet everyone." You would say that because you have not yet met us :).