Dear Sir or Madam,
I would like to apply for the position of salesman advertised on your company website. Your esteemed company is looking for an experienced, qualified and conscientious contributor that I should be a suitable one.
My name is Bill Gate. I am a graduate of Ho Chi Minh City Marketing University and currently work as a salesman at Facebook.
I have been working in the marketing field for five years. My advantage is to know many clients and my connection built with them would help your company a lot.
The only reason for me to leave my current job is that my parents have both retired and they are now living in the city far from where I am working now. Therefore, I decided to apply to your firm so that I can look after them.
I would certainly be interested in hearing from you and wish to have an appointment for an interview. For your convince, I have enclosed my resume.
Looking forward to receiving your reply.
Regards, 
Dear Sir or Madam,
I would like to apply for the position of salesman advertised on your  
company
 website. Your esteemed  
company
 is looking for an experienced, qualified and conscientious contributor that I should be a suitable one.
My name is Bill Gate. I am a graduate of Ho Chi Minh City Marketing University and  
currently
 work as a salesman at Facebook.
I have been working in the marketing field for five years. My advantage is to know  
many
 clients and my connection built with them would  
help
 your  
company
 a lot.
The  
only
 reason for me to  
leave
 my  
current
 job is that my parents have both  
retired and
 they are  
now
 living in the city far from where I am working  
now
.  
Therefore
, I decided to apply to your firm  
so
 that I can look after them.
I would  
certainly
  be interested
 in hearing from you and wish to have an appointment for an interview. For your convince, I have enclosed my resume.
Looking forward to receiving your reply.
Regards,