I know that it is said that staring into the void will cause people to go insane, but how exactly is that done? are there windows on the ship that if you look out of it while in warp travel you will go insane? I dont think this was really explained in the book, I know Navigators can look into the warp with their third eye fine, but how would a normal person do this and how is it treated if he does?

Well, I'm not sure what's canon but the Gellar Field and it's bubble of reality may block the warp.

Alternatively, the ship could have several automatic shutters to prevent seeing the warp, or maybe no windows at all. There's no real reason for them, space is quite dark and 40k ships are prone to being shot at.

Obviously the observation dome is off-limits during warp-travel.

As for the effects, the warp is a place of chaos, but also a psychic reflection of sentient minds around it. Synethsisia (Experiencing one sense as another) is a good start for minor exposures such as warplight reflected off a wall as the character rushes to hide under the blankets. A high-level fear check already has rules for insanity and corruption as a result, so I'd go with that.

Major exposures, or voluntarity staring into unprotected warp, should be described briefly and left to the imagination. If it happens to an NPC, the players should find him shivering, throwing himself into walls and babbling incoherently, or just a smear on the floor. A PC incident would bring them to the edge of sanity, possibly roleplay parts of their delerium until a warp entity ofers them salvation, for a price. The players are exactly the sort of people chaos tries to corrupt.

That makes alot of sense, thank you.