Can't attack!

I think Hikari talking about how to beat someone magickly and how to protect. If this is problem then there are many ways.

Like the other said above its not like a fire ball etc... it will take practise, but dont do it too much because it can tire you out by wasting all of your energy, Practise like 2 mins, then build up the time once your more experienced.

Your intent was right. Perhaps you need to learn how to manipulate the energy in a way that would cause harm. You life Energy naturaly heals, you would have to do something different to cause harm, maybe visualize the energy as black

If you are truly intent on attacking people... Well, a lovely book put it best:

"when people ask me why a witch would carry a shotgun, I tell them, yeah while there may be ways to fight with magic, it's much simpler in the heat of battle to pull a trigger."

In other words... The more conventional attacks may be the easiest and most reliable... I'm not telling you to go shoot people, (granted only because of potential legal reasons) but be realistic here.

If you want protection against enemies, carry a gun. If you want to hurt your enemies, without anybody knowing that it is you, then energy work such as what you are attempting would be the way to go