help help could you modification my dialogue - Help, help! Could you please modify my dialogue?

A:Hello, today you are looking so beautiful.
B:Thanks, I changed my hairstyle.
A:Do you want to have dinner with me this Tuesday? 
B:Oh, I'd like to, but I can't. I have to go have to class.
A:When are you free？
B:I have no time from Monday to until friday.
A:Oh, I see, could we make it some other time then？How about another time then?
B:Ok！I will be free time this Sunday.
A:This sunday would be fine. Do you perfer Chineses Chinese food or western food？
B:I like Chinese food. What about you？
A:Me too. Shall we go to a Chinese food hall restaurant？
B:Good idea. What time on Sunday？
A:At 6:00 o'clock on Sunday night.
B:That's ok (That sounds good/ That's fine). I will be there on time.
A:Fine, I looking forward to it.
B:Me too. Thanks so much for asking me.
A:See you this Sunday.
B:Ok！So long for now.

That was very creative; good job! You might want to take a look at the blue spaces I entered into your text. Each of those blue lines show where you need to put a space between punctuation marks and words. You have to put at least one space between a period or a comma and the next word. Do not put more than two spaces before a new word, though. Also, you might want to review the rules of capitalization for English. The rules for capital letters are kind of unusual compared to other languages. 

I hope this helps you! Please let me know if I can help you again.

help help could you modifiy my dialogue

A:Hello,today you are looking so beautiful.
B:Thanks,I changed my hairstyle.
A:Do you want to have dinner with me this Tuesday?
B:Oh, I'd like to but I can't. I have to go to class.  (This is more natural.)
A:When are you free？
B:I have no time from Monday to Friday.
A:Oh, I see, Could we make it some other time then？
B:Ok！I have free time this Sunday.
A:This sunday would be find. Do you perfer Chinsese food or western food？
B:I like Chinese food. What about you？
A:Me too. Shall we go to a Chinese food hall？
B:Good idea. What time on Sunday？
A:How about 6:00 o'clock on Sunday night? (Yours wasn't wrong, but this is more natural.)
B:That sounds good. I will be there on time.
A:Fine, I'm looking forward to it.
B:Me too.Thanks so much for asking me.
A:See you Sunday.
B:Ok！So long for now.

help help could Can you please help modify my dialogue?

What you wrote is not wrong but a bit too formal between friends.  It sounds very artificial.

A:Hello.__today you are looking so beautiful Aren't we looking spiffy and gorgeous today! 
B:Thanks.__I Just changed my hairstyle.
A:Do Would you want like to have dinner with me this Tuesday? 
B:Oh,I'd like to but I can't.__I have to have a class.
A:When are will you be free？
B:I'm busy have no time from Monday to Friday.
A:Oh,I see. Could we make it Perhaps some other time then？
B:Ok！I'll be free time this Sunday.
A:This sunday would be findGreat!  Do you perfer Chinsese food or western food？
B:I like Chinese sounds wonderful. food.  What about you？or "And you?"
A:Me too!__Shall we meet go to at that Chinese food hall？
B:Good idea.__What time on Sunday？
A:At 6:00pm will be fine. o'clock on sunday night.
B:That's ok Great!__I shan't be late. will be there on time.
A:Fine,I shall be looking forward to it.
B:Me too.__Thanks so much for the invite. asking me 
A:See you this Sunday then.
B:Ok！So long for now Bye/Ciao/See ya/.