So i am not too sure how to word this during a paper match. Let's say I have Young Pyromancer already on the battlefield and I cast Village Rites. Would Young Pyromancer's ability go on top of the stack and create the Elemental first which I can then can use as part of the casting cost of Village Rites?
701.4a To cast a spell is to take it from the zone it's in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect.
I think Philip Kendall's use of the word "before" is unclear. Paying costs doesn't happen before casting a spell, it happens during. Paying the costs is part of what it means to cast a spell. Taking the card from the hand, putting it on the stack, and paying the costs are all one game event called "casting". Young Pyromancer's ability is a triggered ability. Triggered abilities don't immediately perform the effect listed, they just put the effect on the stack. When you cast the spell, Pyromancer's ability doesn't create a token:
603.2. Whenever a game event or game state matches a triggered ability’s trigger event, that ability automatically triggers. The ability doesn’t do anything at this point.
Instead, it puts "create a token" on the stack:
603.3. Once an ability has triggered, its controller puts it on the stack as an object that’s not a card the next time a player would receive priority. See rule 117, “Timing and Priority.” The ability becomes the topmost object on the stack. It has the text of the ability that created it, and no other characteristics. It remains on the stack until it’s countered, it resolves, a rule causes it to be removed from the stack, or an effect moves it elsewhere.
By the time "create a token" resolves and you create a token, the action of casting the spell (including paying the costs) has been completed, and the spell is already on the stack. You do create the token before the spell resolves, but not before you pay the costs.