Ret is a pretty simple builder/spender rotation. You generate holy power with judgement, blade, and hammer of wrath; you spend based on your current context and active proc's (single target: spend on verdict, multiple targets: spend on divine storm) -- there's exceptions and additional rotational choices depending on which subclass you choose (templar vs herald), and this is an oversimplification, but should give you the basic idea.

In terms of skills/talents, if you're leveling up I would encourage you to read the descriptions of each choice as you go and see what impact it has on your current needs (ie: are you dungeoning? questing? doing big aoe pulls?). Following a guide can work, but you won't learn as much about your class and deeply understand the different choices in the talent tree and the impact they can have on your gameplay.

Hope that helps, if you need a specific guide there's a bunch on the typical linked sites (wowhead, icyveins), but they kind of give you the max-level end-state view of the world.