proofreading

Hello, would you please be kind enough to proofread this paragraph to me? Are there any errors in my self made paragraph?

Thank you

Hello,
I am an English Literature student in Iran. Sometimes we need to give a lecture about a specific poet in the class in front of our classmates (50 students that 90 percent of them are females). But when I myself do that, I get stressed and the beats of my heart increases over and over. (Sometimes this stress makes me blunder while giving lecture as if I was afraid of something)
In fact I don’t know why I get shy and stressed when I give a lecture to my classmates. (most of them are females)
Is there any guidance to reduce my stress? Would you please help me? How should I overcome it?

I have indicated my suggestions in capital letters:

Hello,
I am an English Literature student in(FROM) Iran. Sometimes we need to give a lecture about a specific poet TO the class in front of our classmates (50 students IN ALL. OF WHOM 90 percent are FEMALE). But when I do that, I BECOME stressed and MY HEARTBEAT increases AGAIN AND AGAIN . (Sometimes this stress CAUSES me TO MAKE MISTAKES while giving THE lecture as if I was afraid of something)
In fact I REALLY don’t know why I BECOME shy (NERVOUS) and stressed when I give a lecture to my classmates, most of WHOM are FEMALE - (YOU HAVE ALREADY SAID THAT)
CAN ANYONE GIVE ME any guidance to reduce my stress? Would you please help me? How COULD I overcome THIS PROBLEM?

Thank you so much. One native English speaker told me that I should not start a sentence with “but”.
Do you agree with him? (In the second line)

Not a teacher. Not a native speaker.

You can start a sentence with “but”.

I subscribe to this view:
uk.answers.yahoo.com/question/in … 734AAcyzd0

Everybody, thank you so much for answering.
In Alan’s second line:

(50 students IN ALL. OF WHOM 90 percent are FEMALE)

Before “of whom” and after “in all” there should be a comma or dot?

And my second question is why not “in the class”? You have said “to the class”.
Why not in the class?

It should be a comma, not a full stop.

You give a lecture to someone (in this case, the people in the class.)

Beeesneees,

  1. How could I overcome this problem of nervousness and stress?
  2. Why do I become nervous when I give a lecture to my female classmates?
    Are these sentences grammatically OK?

possible

Many thanks.

Beeesneees,

  1. “How could I overcome this problem of nervousness and stress?”
    Can I write this above sentence as below:
  2. “How can I overcome this problem of nervousness and stress?”
    Do they mean the same irrespective of tenses?
    Thanks.

Yes - they are the same tense, but the verb is different.