Learning skills from another campaign

Hey, I have both Prophecies and Factions, but I only have a character in the Prophecies campaign at the moment. After I installed Factions, I noticed new skills were available from the Priest of Balthazar for my Proph PvE character, which I unlocked, but forget I had to learn them too in order to use them. So my question is: How does a PvE character from one campaign learn skills from another campaign? I assume it's possible because these skills wouldn't show up at all if they weren't available to use, right? Thanks guys.

To learn a skill from another campaign, you get your character to that campaign first via a quest from the hub city (Lion's Arch in your case). Then you just buy it from a skill trainer in a city from that campaign.

or, for Elite skills, you go out and cap them in that campaign.

You also can unlock skills using Balthazar Faction and then use tomes to learn them.

Skill trainer from the campaign the skill is from or tomes, since you've unlocked them already. There's a skill trainer in Kaineng,, which already has an extensive list of available skills and would be the first city you get to when crossing over from Proph to Factions.