Arduino leonardo problem

Hi, i bough a arduino leonardo r3 to make a wheel steearing but i don't know how to ENTER IN BOOTLOADRER MODE becaude when i try tu upload hex file with Xloader i can't. Can you help me?
If this problem don't have a solution, how can i se the code inside of the hex file?
Thank you.

You can enter the bootloader mode by pressing the reset button. This will cause the LED marked "L" to pulse. Note that it only stays in bootloader mode for several seconds before timing out so you need to start the upload process while it's still in bootloader mode.

how can i se the code inside of the hex file?

You can never get the Arduino code out of the hex, because the hex only contains the compiled program after it's been through the compiler. You can use avr-objdump to get the assembly code from the hex file but that will in no way resemble the Arduino code the hex was compiled from.