The Rede is a rule or law that most Wiccans live by. The short version is:
Eight Words the Wiccan Rede Fulfil:
An It Harm None, Do What You Will
There is a longer poem called the Wiccan Rede, but the essence of the rule is that all things are acceptable so long as no one is harmed. Not all Wiccans interpret this the same way, and many follow it to different degrees.
A ritual is any ceremony that has spiritual meaning for the person performing it. Rituals can be simple or elaborate and complex. A ritual with a specific intent is more often referred to as a 'spell', but rituals can also be used for celebration, worship, meditation or other astral work.
Runes are symbols from an ancient Nordic alphabet. Each symbol has a meaning and these symbols are often inscribed on jewelry or altar tools. A set of wooden pieces each bearing a single rune are used in divination.