This guide might help (though it isn't a video).
I'll also gladly walk through a Seoni combat check for you. Let's say she has to make a Combat 9 check to defeat a monster. She has no attack spells in her hand, and no skill feat or power feats checked off. So she's going to want to use her power: "For your combat check, you may discard a card to roll your Arcane die + 1d6 with the Attack, Fire, and Magic traits. This counts as playing a spell."
So....
Determine which skill you’re using. Seoni's power allows her to determine the the skill is Arcane, which for her means it is also Charisma. She has to discard a card to do this. Any card will do, it doesn't matter which type. Let's say she discard's a Strength spell.
Determine the difficulty. It is a 9.
Play cards and use powers that affect the check (optional). Seoni and her companions can play other cards now to add to the check. Let's say Seoni has a Blessing of the Gods. She discards that to add 1 die to the check. Merisiel is one of her companions, and though at another location, she can also discard a Blessing of the Gods to add 1 die to the check.
Assemble your dice. Seoni picks up her Charisma d12, the d6, from her power, and 2 more d12s from the blessings. So 3d12 + 1d6.
Attempt the roll. She rolls the dice and adds up the total, plus the +2 for her Arcane skill. The total is 9.
Take damage if you fail a check to defeat a monster. You didn't fail, so no damage.
If you had failed, lets say by 2, you would be dealt 2 Combat damage. If the monster had a power that said "All damage dealt by this monster is Fire damage" it would be two Fire damage instead of 2 Combat damage.
Seoni can't recharge the Strength spell, because she didn't play the Strength spell.
I hope that helps. If you want to ask a followup question, feel free to do so.
In terms of the card game, how is Fire Damage different than Combat Damage? Is the distinction only relevant if you are playing a certain card to block damage (for instance if you are using a type of armor that doesn't have Fire or something like that?)
Pretty much. Typically it makes armor harder to use. Nine times out of ten that effect text may as well not be there for my groups.
EDIT: It will be an effect on the card that blocks the elemental damage, not something hidden in the traits or whatever. So if a shield says it has the fire trait, that doesn't necessarily mean it can block fire damage. It has to actually say it does so in the powers section.
Just for future reference as well, when you are dealt Ranged Combat damage, it is both Ranged damage and Combat damage. It can be reduced by armors that reduce Combat damage, armors that reduce Ranged damage, or armors that reduce all/any damage.
In terms of the card game, how is Fire Damage different than Combat Damage? Is the distinction only relevant if you are playing a certain card to block damage (for instance if you are using a type of armor that doesn't have Fire or something like that?)
A lot of armors have one power to reveal/recharge/discard to block combat damage and another power to block all damage of any type but you have to bury/banish the armor. So Fire, Acid, Poison, etc. damage is usually harder to deal with.