Valhalla is the hall of the fallen warriors in Norse Mythology, Valhall is two compound words: Valr( meaning "dead body on a battlefield)  and holl( meaning hall).

Odin decides the outcome of every battle in Midgard, everytime a battle breaks out he sends the Valkyries down to  Midgard to observe and choose the bravest of the fallen warriors to bring back to Valhalla.

The Prose Edda tells us that half of the fallen will go to the field of Folkvangr and that Freyja has the right to pick the first half of the fallen warriors.

It has been proposed that Folkvangr could be another name for Valhalla. However, this does not remove the importance of Freyja from the equation.

She might be the one in charge of the Valkyries, and ny her having the first pick, could have been done to show how significant she is.

The chosen ones will be greeted, with a horn filled with mead at their arrival in the afterlife, they won't see any of  their loved ones 

In Valhalla unless they also died bravely in battle, anyone who has not been chosen by a Valkyrie will go yo the queen of Hel.

According to the poem known as " Griminismal", the gates of Valhalla are so wife that 800 soldiers can walk through it side by side. The roof is decorated by Sheild's, and held up by spear shafts, with chainmails laying on the benches.

On the western door hangs a wolf, and above him an eagle, Valhalla is enormous, with 640 rooms, many of which dedicated to the large army of Einherjar( lone fighters), the greatest army of them all.

" six hundred doors

And still forty more,

I believe, are at Valhalla.

Eight hundred einherjar

Will go together out each door

When they go to fight the wolf"

-Grimnismal 18

Valhalla, contrary to some Beliefs is not a place where you can sit on a cloud while playing a harp, nor do you get 72 virgins; in fact, Valhalla is an afterlife for warriors, where everyday they will practice with an axe, spear, and sword,  preparing for the battle of "Ragnarok."

It does not matter if they have their arms,legs, or head chopped off, because while in valhall, they are immortal.

"All the einherjar

In odins home fields

Fight among themselves each day.

The slain they select 

Then ride from the battlefield,

Reconciled they sit again together."

-Grimnismal 41

Every evening they will join Odin in the huge dining room, where they will br served pork from the boar Saehrimnir, and mead from the goat Heidrun, the only one who does not eat is Odin, he only drinks wine,  feeds his two wolves Gerd, and Freki his portion if the meat while enjoying the company of the warriors.

"Andhrimnir has

Saehrimnir boiled

In Eldhrimnir,

The best of meat.

But few know

On what the Einherjar feed."

-Grimnismal 18

" Geri and Freki

Are fed by the battle skilled

Father of armies;

But on wine alone,

Weapon glorious

Odin ever lives."

-Grimnismal 19

The correct way to say "to valhalla" in old Norse is "till valholl", the reason why its genitive form since it follows the preposition "to" (old norse: Till).