Help with Macro please

So many buttons to push and stuff like that. Playing Holy Priest. I was reading where you can create macros that with mouseover option on that it can either heal me or party member by casting a spell, but if mouse is over an enemy it casts a damage spell. All with the same button.

Is that possible? If so, anyone post one? Hope I explained that correctly.

Yes, I think you have explained correctly, and if I have understood correctly, the structure you want is like this

#showtooltip WHAT_YOU_WANT_TO_CALL_IT
/cast [@mouseover,harm,nodead]HARM_SPELL; [@mouseover,help][help]HEAL_SPELL; [harm]HARM_SPELL;[@player]HARM_SPELL

Example:

#showtooltip Flash Heal
/cast [@mouseover,harm,nodead]Smite; [@mouseover,help][help]Flash Heal; [harm]Smite;[@player]Flash Heal