How much background information

[Darkild]

Currently at the last part of Skinsaw Murders - ROTR adventure path.

Recently i've found my sessions less enjoyable for me, my players are having fun, but i'm missing something.
I simply wish my players knew more of the backstory, but i'm finding it difficult to give them the information needed to understand/discover the plots without ruining the story for them. I've played with the thought of simply telling them out of game, what's going on behind the scene, but...yeah..i can't decide if its a bad move.

I told one of my players this and he asked why i didnt just let them read for example Ironbriars journal...their linguistics rolls where simply so low that it didnt make sense that they could, in hindsight i should just have let them read it, but after describing the cryptic text i thought it would undermine the difficulty. Also I find it weird that bad guys have journals and even more so journals with detailed background information...

So my questions are:
1. Is it a bad move telling them the backstory?

2. How much background information do you give your players, either in game or out of game?

3. Any pointers as to how to give them more background information in game?

[Darkild]

Ohh and i'm not thinking specifically about the rise of the runelords adventure path but any adventure really.

[Corsario]

I feel your pain.
What I have done, in occasion, is doing "cutscenes" where they "see and hear" the bad guys side of the story.
They know the backstory, but have to play "pretend" they don't with their characters.

[Nathan Monson]

I do tend to tell my players some of the non-spoilery bits of backstory; things like villain motivation, some of the backstory stuff like that. my players don't mind, but it sounds like yours do, and would rather read about it IC, so I would keep having, notes, journals, overheard conversations, stuff like that.