depends on which program u use.. on gimp its easy to make a spinning head
1. Filter
2. Animation
3. Spinning Globe
and then u set how much pictures the spinning should have (if u set more it will spin slower) then u got a new window. save the spinning as .gif and as animation (should stand there) and then it works..
watermark... just write with any tool over the complete picture so no one can use it without that word or whatever u made over it (but save thas as seperate picture, instead u destroy your good maked head)
but thats only for GIMP so i dunno about photshop or other programs