how do you build a ?satr? shrine?

what things are needed
Explian all of them please

What do you mean by shrine?

Do you mean a Ve?
If so, there is a wide variety of opinion on the matter. For modern practical purpose, a Ve is a place set aside for the honoring of the Gods, Goddesses, Disir and Vaettir. It can be as elaborate as a specifically manicured grove of trees or bushes, or grassy yard, to something as simple as a corner of your bedroom set aside just for that purpose. The pertinent aspect is that it is set aside. It is specifically for the honoring of the Gods, Goddesses, Disir and Vaettir.

A stead?
If so, then we have what amounts to an ancient version and the modern version.
The ancient meaning of stead is ones landholdings. The home-stead.
For most modern usage in my experience, the stead is wherever the ritual is taking place (the venerable Hammer-Hallowing contains within it: "....hold and hallow this holy stead..." in referencing a workspace or area where a ritual is occurring).

A Hoff?
If so, this generally (now) refers to a structure used as a dedicated gathering space for the honoring of the Gods, Goddesses, Disir and Vaettir. A "temple" if you will. Again, this is in my general experience amongst Asatruar for the last 15 years.

A simple altar?
If so, you need a flat piece of wood, or stone. Whatever items you wish to put upon it (usually a Hammer, at least), and a spot to put it on.
Something to remember about Asatru... it's more about function than form. Form is nice where it's practical, but functionality is of higher importance.

weal, I can only tell you my own experience. I have a smallish altar in a corner of my room, it's made of three slabs of unseen stone (IMO, natural works best). You can also use wood.
Make sure it's big enough so you can put items on it.

A friend of mine uses one made of stone slabs likewise, but in the middle of the horizontal one, it has a hollow which he filled with soil. He uses that for liquid offerings (mead, ale, blood), so that the liquids don't spill all over the place.

Shrine isn't a term commonly used in Asatru. But I get what you're aiming at.

I am currently a reluctant apartment-dweller with limited personal space and none of it outdoors. I have dedicated a wall in my bedroom as altar space and have a large and rather nicely decorated piece of wood shelving (language is failing me here, as it is actually a series of three shelves enclosed in a frame... but I don't know if that sort of thing has an official name). In any case, I jokingly refer to it as my "Walter" (short for wall altar). The top level is for gods and other divine powers... here I keep my Thor's hammer and statue as well as some smaller items. The second is for wights and ancestors, with a special "Norn cauldron" representation in the center. The third level is more of a personal level concerned with living kin and general items that connect me with general aspects of the faith and culture such as rune stones and a family heirloom or two.

Now my kinswoman, who has land that is expected to remain in the family, has dedicated a vie in her garden. It is a pillar of stones that have been piled above a specially dedicated hoard, with a flat stone on top where offerings can be placed or poured out.

I would agree wholeheartedly with what others have said, that function and practicality take precedence over form.