I got the core and some battlepacks. I have read the rules but I am still confused on deck building....

I understand you can have other order races with other order races etc... but what do you pay for them? I see that you pay the 1 orc symbol for free cuz its on my orc kingdom and I need to pay an extra for each other orc symbol on the card.. but let's say I want put a chaos card in my deck too.. how do I pay for it's cost to be put into play? Say it is a 2 cost with 1 chaos symbol... Would it then be 3 to put in because I don't have a chaos symbol to make it cost less??

Well, you can only include cards that belong to the same type: either Destruction or Order, along with neutral cards.

You pay for their cost the same way you do for the your capital's faction: paying the top left corner amount in resources, and then, if any faction icons are present, you can forfeit paying for as many as there are icons of that type on the table, if not fulfilling the amount indicated in the card, then pay the rest in resources.

For example, let's say I'm playing with the Orc capital, and have a deck composed of Orcs and Chaos. When I put in play a Chaos card, or play a tactic, I need to pay the cost in resources, plus any Chaos icon in the card, unless there are other Chaos cards already in play, then I can subtract the number of total number of Chaos icons in play to the total amount of Chaos icons in the card.

I hope this helps a bit, though it's a bit convoluted.

So let me try to clarify something. The capital has a default 1 symbol. I'll say i'm playing an orc. I want to play a chaos card who is 2 resources and 1 symbol, so I need to pay 3 resources to play it. Because I now have a chaos symbol in an area, it acts to cancel out when I play another 2 cost chaos card with 1 symbol on it, making me only have to pay 2 instead of 2 plus 1 symbol?

That's exactly right!

Does the same work for the orcs? I play an orc guy, who has the 1 orc symbol. So if I play another Orc guy who requires 3 plus 2 orc symbols. The capital counts as 1 and the other guy counts as the other and I just need to pay the 3?

Yes, that is correct.