>About myself... I am female, who graduated from Seoul National University.
>I have had much experience to teach English & Math for students.
>I am staying in Singapole now, and would like to stay here more.
>So I would like to homestay and at the same time teach English or Math.
>(Of course both are possible)
>
>If somebody is interested in me, please contact on this email.
>jullean@hotmail.com
>In case you leave your phone number, I will call you.
>
>Actually I am very urgent.
>If it is impossible for me to find out homestay, I have to leave in a week.
>I hope I will be able to get more wonderful experience in Singapole.
>And about myself, I can prove all my identification to you.
>
>Thanks.
>
>

What made your staying in Singapore depends on finding "homestay"..?
Does this mean the landlord needs to be a guardian for you..?  Can't quite understand your situation.
If you're seeking any illegal stay here, I would rather advise you not to do so.  
And your grammar seems to be not enough to teach the others..sorry for not very positive reaction.