Look at your motherboard. Usually see you at DEL.
But some are F1 and some are F2. Today's wireless keyboards can be identified under DOS.
But it also depends on the BIOS version.
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Some board BIOS USB keyboard option is off, so boot can not use wireless keyboard operation, you can find a PS\/2 connection to open the USB keyboard, later you can use wireless operation
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The current wireless USB device should not be used before entering the operating system, because the current BIOS does not support it.
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For the general motherboard, the way to enter the bios is to restart, the device recognizes the keyboard, long press Delete, you can smoothly enter the bios, such as Asus, Gigabyte, etc