The cycle itself
The moon takes roughly 29.5 days to go from new moon to new moon. Waxing means growing towards full; waning means shrinking towards dark. That part is astronomy, and you can check it yourself by looking up.
How Wiccans commonly use it
Many practitioners use the waxing moon for beginnings and growth, the full moon for celebration and clarity, and the waning moon for release and rest. Full moon gatherings are often called Esbats.
Traditions vary
Some covens meet at every full moon; some solitary practitioners barely track the moon at all. Neither approach is more Wiccan than the other.
Growing moon: start things. Full moon: notice things. Shrinking moon: let things go. Optional, all of it.