Developing a ritual depends on what kind of ritual you're doing. (eg. honoring, offering, etc)
I've never seen Charmed, so I can't say if they work, but if you have a specific intent you can search herbs here (http://www.unc.edu/~reddeer/magick/herb.html). Be careful with toxic or poisonous plants.
Energy is just what it is; if you jump up and down a bunch you say you used energy to do so. When you chant, dance, sing, meditate, speak from the mind, whatever, you raise energy. If you love someone, for example, you get that "fluttery" feeling; this is an example of energy, in that you feel very strongly (this is emotional energy).