Now I understand that the question was "Wiccan spells" and not spells in general. This can be quite controversial, because I know that many Dianic Wiccans would argue that men have no place with the goddess as they believe more femanine energies (namely the goddess) to be their patron dietie(s). Although, there could be just as many Dianic Wiccans to argue against that going back to traditional wicca where men have their riteful place and keep a masculine balance.
Either way, I believe men, boys, whomever can practice wicca if they really wanted to.
I would not consider it to be sacred to just females, such a thing would degrade the spiritual journey. In general, a religion that rejects certain people is not open, and there for not enlightening to practitioner wishing to experience more in the spirit realm.
I would just go with whatever is comfortable for you, why succumb to the dogma thought by others?
wicca is a religion, it teaches there is male and female in everything, so it's not just for woman. typically, though teen girls join wicca because, as i said 'typically', they wish to rebel or be different, or cast spells, or saw a movie/show with witches and think they can fly/make people love them/shoot lasers from their fingers.
you don't need to be wiccan to cast spells, and you don't have to cast spells to be wiccan. spells are basically using energy to help yourself. there's no real religion to it. if a spell says you need to pray to the horned god and triple goddess but you're Hindu and pray to Kali, then pray to her, there's no real difference. all it means is, you believe in one deity and not the other. [however if it calls for a male and female, you might want to use a god and goddess you believe in.]
i have a few male wiccan friends, but yes i have more female, i don't know why that is, but you don't need to be a certain, age, race, gender, sexual orientation, or like coke/pepsi. wicca basically says if it feels right to you, then you should do it [that and don't harm anyone or anything] if you feel the path is right for you, then do it.
a male wiccan can be called a witch. i've met male witches who call themselves that because historically 'warlock' was an insult for male witches. don't know why they don't call themselves 'wizards' i think it's cuz when you say wizard most people think of Harry Potter or Lord of the Rings.