letterhead

A letterhead holding stationary.

No, you have spelled letterhead correctly as one word.

Letterhead stationery has the organization name printed at the top of the page.

I presume letterhead is the name at the top. Writing on letterhead paper gives an authenticity to the origin of a letter. (Desktop publishing has no doubt diminished its value as an indicator. )

There are a lot of free letterhead templates available online. Microsoft offers a lot of letterhead templates that can be downloaded onto Microsoft Office and printed.