castlilng in Chess960

howe is castling done in Chess960, i mean will I have to move the king where? and the rook? and which first?

Castling in chess 960 will give you the answer...

The short one is that you get O-O and O-O-O links under the board when you can.

You need all the pieces between the King and the Rook to be gone and your King can't pass over a square that would place it in check and you can't castle when in check. After castling the King will end up on the G-file when castling Kingside and on the C-File when castling. The Rook will end up on or stay on the F-File after castling Kingside and the D-File when castling Queenside.

On a related note:
Chess960 and Why do great players make poor inventors