MacroFollow

Hi everyone! I'm happy to have successfully pass the first 5 days of WoW and still enjoying it. I started making macros to use while I'm in party. I made a macro to pull with a wand that goes like this:
/cast Shoot
/p Incoming %T

Now I want to make a macro to use an item in this case a Minor Soulstone. What I want is to be able to use it (after making a Minor Soulstone manually) with the help of a macro instead of going into my inventory (losing precious time), search for the Minor Soulstone and cast it on a player who's about to die. I know you must use the command /cast for anything that's in the spellbook but it doesn't work for an item in your inventory. How do I do that?

Thank you for your help.

Yes I can but I would like to use it in a macro to automatically let the player who I cast it on know he can respawn due to my Soulstone.