Help! I have got one part of the disc? that you need to open the shadow door the one by passing the test that the statue gives you. Where do I get the others?

I'm a little confused, are you asking how you open the shadow doors, or how you get the symbols of Amaunator?
There's another sun gem in a statuette beyond the room with all the letters on the floor. You can use it to open the final shadow gate.
You get a segment of the symbol of Amaunator by giving the shade past the lava room her remains, which are found in the crypt at the beginning of the map. The final part is beyond the lettered floor room, in a hidden panel on one of the room's walls.