Try to be concise, and don't write too many pleasantries, which is immature and not suitable for this formal occasion.
Let me give you an example for your reference.
Dear HR (Manager Zhang/Mr. Zhang), hello!
See the attachment for my resume. Please check it! Hope to get your favor!
I wish you a happy job!
mfkmpxa？
2010/0 June 13
In addition, pay attention to changing the name of the attachment to the format of "position name+name", such as "Personnel Commissioner (mfkmpxa)"