To earn Mod points for your Combat Arts you need to level up the associated Skills for that Aspect. So, for example, if you are playing a Seraphim and want to Mod the Pelting Stike CA then you need to level up your Exalted Warrior Focus and/or Tactics Lore skills. The first mod points come quickly, but as you level your skills they come more and more slowly. There are also three sets of mods. The first two are the Bronze mods and you can take one OR the other, but not both. The second two are the Silver, and the last two are the Gold. Again, for each group of mods you can take one or the other, but not both.

Also, if you post this same quest on the Boards with details on the class and aspect and combat art we can give you detailed answers.

And, you can see all of the classes with their combat arts and what the various mods do on the Sacred Wiki site.