I know that this is a VERY LONG post, but I hope that you
(Bonta-Kun) will take time and read it... 
It may just be pure infatuation in this case...
My suggestion is also not to think too much about it... try to keep
this matter at the back of your head and get to know her better as
a friend...
From your earlier post, I can tell that you are a Junior College
student... Your studies are important. Do not let this issue cause
too much distraction to your studies. Get to know her in person,
maybe you can kindly ask her for her MSN contact and talk to her
online whenever you are free. Engage in healthy conversations with
her; and maybe if she needs help or if you need help in certain
subjects, you can request to help her out after school/request if
she is able to solve some of the questions regarding the subject...
(my point is to make your conversation related to schoolwork - try
not to talk too much about it and eventually bore her.) You can
also suggest recommending and exchanging songs via MSN Messenger
that can beat stress... Since you are still studying, I don't quite
recommend you to appear on MSN online for an entire day just to
wait for her, alternative methods like emailing her on days when
she is not online and when you are free to do so is a good method
of keeping in contact with her... then wait for her reply soon. You
can check the inbox everyday, but keep it short (10 to 20 mins) and
get back to your work.
That's quite a good start! Now, let's not go too far into
thinking that you two will be lovers just yet but my advise for you
is: aim to strike a friendship with her first, get to know her
better...
Keep those thoughts of being her boyfriend and potential husband
aside first, these thoughts will usually hinder you from knowing
her better... even before you step in front of her, you will surely
back off because you are shy... Keep the thoughts and feelings at
the back of your mind... You can approach her and get to know her
name, which class she comes from, her email address and tell her
that your intent for doing so is plainly to be her friend. I know
that you want to be someone closer to her than just being her
friend, but remember that for a succesful relationship to be
birthed forth is the careful and steady development between the two
from being just friends to closer friends, best friends to
lovers... you have to be her friend first in order for it to start!
It is quite a good start to do something good for her, now build up
the relationship with her starting from just being friends...
Try to approach her one of these days at her most convenient and
accessible time in school, do not ask someone to get her contact
info on behalf of you - that's not being very sincere. Try to
accomplish this first task by yourself, you can choose to approach
her when she is either alone or with a smaller group of friends.
You may ask any other guy in her class for the timetable, so that
you know her schedule in school and plan your approach...
My opinion about you sitting beside her may not be a good idea.
You may start to feel jittery or very out-of-place sitting beside
her... By then, she might have already sensed that you have
feelings for her or feel strange about you... Get hold of her email
address and message her online or email her if you feel shy talking
face to face with her. Don't ask for her handphone number just yet!
Until you think you are ready to do so, after a few conversations
ou have with her online...
Girls are sensitive creatures, their emotions and feelings are the
first to be affected by every sentence spoken to them... Do not go
up to her and make a scene like what Xephone_xenon has mentioned,
it will surely embarrase her and cause her to hate you forever; or
it will probably give her a totally wrong impression of who you
really are.
Be sensitive to what you say and do to her... 
Erm... do not follow this "script". Just do whatever seems right
and appropriate for you to do at the certain time and place. This
mini-conversation seems very awkward, you are making her do
something that inconveniences her... please do not follow! Sorry
keekx! Craft a better story for our dear brother to follow next
time! Girls these days will not waste their time doing something
pretty useless like such, I think she will reject your request in
the above situation.
---
Before I end my post, I wish you the best of luck getting her email
address and getting to know her better! Feel free to message me at
my Mailbox anytime you require my help... Please do not let this
junction of your life affect you too much, continue to work hard in
your exams no matter what happens and get into a University after
your years in JC. Most girls would prefer to go with smart guys.
All the best for your studies, Bonta-Kun, see you soon bro! Give
her a good impression of yourself and be her friend! 