Business Letter

I always need to deal with business letters because of my job. But i don't know how to write them more professionally. So can anybody help me with my business letters? Or give me some advises about what kind of letters would a native English speaker want to receive?
Here's my letter below:
Dear Mr/Ms ××：
This is Allan from ×× company. I'm glad to hear that you're on the market for water color pens, our company specialized in this field for more than twenty years, with good quality and competitive price. We're looking forward to a long-term and friendly cooperation. Should you have any questions, please be free to contact me.
Best Regards!
Allan

Happy Thanksgiving!

Its Thanksgiving day!
Even though <strike>the</strike><strike> </strike>we don't celebrate it here in China, <strike>but</strike> I think it is good thing for people to take a day off and be thankful. Miracles happen when you start to count the blessings you have.
I'm grateful that I'm healthy and able to sit in front of the computer and type. This means my mind is functioning normally, my eyes see clearly, my fingers coordinate perfectly.

Live the moment. Be happy! ~(^_^)~

This is an awesome ^^. The last part was so poetic 加油~~~ :)