You are right, I learned by using pages like wowwiki, thotbott, wowhead, etc.
First, I suggest you to look for a guild. There you'll have people that can help you level or can answer any questions that you may have.
You didn't mention which level are you. When you are a Night Elf, you start at Aldrassil, Teldrassil. You should take every quest that's there, and do it. When you are done, you should be around lvl 8. Next, you go to Teldrassil per se. That's a large place with lots of quests. You may end all of those quests and be like level 12-15 if you kill a lot. Then you find Darnassus, which is a capital city. Like Stormwind City, Ironforge, etc. At Darnassus you can use the Auction House and sell things you dont need. You need to make money to pay for your trainings, mana drinks, armor repairs, the mount, professions items, many things. You have to go to a Priest trainer every 2 levels. For example, at level 20..then 22. Also, every npc that says ''merchant'' can repair your armor. When the durability of for example your boots, its 10/55, you need to repair it.
To make more gold you have to take a Profession. You only get to choose 2, so choose carefully. Make sure you pair the professions, like Skinning & Leatherworking, or Tailoring & Enchanting, Herbalism & Alchemy, etc. Sell it on the Auction House. When someone buys it, the money ends up in the mailbox that's normally close to the Auction House and Inn. When you buy something too, it ends up there.
Fishing and cooking are secondary professions. When you cook, first need to click on the fire, and then you click on Cooking, click create. You need to buy/have the ingredients.
So,you get out of Darnassus, using the pink portal that's close to the bank. There you take a gryphon or the boat to Auberdine, Darkshore. You set your hearthstone there and level until lvl 20.
When you reach level 20, go back to Darnassus and buy a mount.
You have a Talents tab, that every level you earn one point. You need to put those points in the talent tree you wish to be. If you want to be a healer, then put your points on Holy, if you want to take forever to level, then Discipline. If you are planning on gaming solo, be a Shadow priest.
http://www.wowwiki.com/Priest_talents
Make sure you are wearing armor that has a lot of Intellect, Spirit, Stamina.
When you are done with Darkshore's quests, take the boat to Stormwind City, and level there, at the Eastern Kingdoms. Because if you keep walking from Darkshore, you'll end up in Ashenvale, which has a lot of higher level hordes ganking around (if you are on a PVP server) BTW, after level 20-25 you'll be at contested territories, meaning horde and alliance quest there. More chance to PVP action.
I suggest you to download the add Quest Helper, and keep reading about the Priest class and other classes too. The only bad thing about casters like Druids, Mages, Priests, etc, is that at the beginning it takes a lot of down time for mana drinks in between kills. As opposed to for example, Rogues, that don't need mana, and can keep on killing until they are done.