To expand on the above a little...
Magic basically splits down into three big chunks. You have
personal magic, which is based on your inner magical energy (called Djed); you have
world magic, which includes things with symbols, rituals, and ingredients; and then divine magic or
gnosis, which you already know about. Essentially, gnosis magic is where your power is coming from the god or goddess who gave you the mark. For personal magic and world magic, that magical power is coming either from yourself, or from nature, so you don't need a gnosis mark.
Personal magic includes things like
reimancy (manipulating the four elements),
flux (manipulating your "chi" to make you stronger or resist pain),
shielding (creating magical barriers), and all sorts of cool stuff. World magic is more things like
alchemy and
glyphing (scrolls and sigils).
The link Raizuvon gave you explains everything, but hopefully that quick summary will help narrow down what you're looking for.