You will need a blue candle for the first calling of Phommett, but it's not required afterward.
Inscribe the candle with the name of Phommett.
Consecrate the candle with your own saliva.
Place the candle in its holder and charge it by placing your hands on either side of it and running energy into the candle until you feel it is fully charged. To help with the charging you may silently repeat the name of Phommett to your self until the charge is complete.
Once charged, light the candle, and call Phommett's name outloud 3 times. You will know he is arrived by a change in the feeling of the atmosphere of the room you are in.
Once he has arrived, state what you need help with. Finding a particular knowledge, how to perform certain types of spells, help activating abilities, maybe even as a stand in to help your casting of a spell. if it is a type of knowledge or magick he can help with it. Be prepared though, he may ask for something in return for his help.
Remember to be polite, and enjoy having one of the old ones on your side.