Change spi pins number

hello please can i change the pins number of spi pins of mega2560 50.51.52 to another pins for exemple 40.41.42 ??? ??

No. Those are the only ones connected to the SPI hardware. You can't change to other pins.

can i define
50=40
51=41
52=42
.
.
ans take the signal from 40.41.42 ??

Not if you want to use SPI. 50, 51, and 52 are the pins that are connected to the SPI hardware. Those are the only pins you can use for SPI.

Not if you use hardware SPI. If you want to bit-bang you can use any pins you want.