For example, I will update the BIOS U30 on the HPE ProLiant DL380 Gen10 server.
First of all, you need to download the archive with the firmware file and unpack it, I will give a download link from the official website (you may have to register):
Then you need to open iLO (the login and password can usually be seen on a sticker on the front panel of the server), the current BIOS version is immediately displayed on the main page. On the left in the menu, select “Firmware & OS Software”, then on the right, click “Update Firmware”, click “Browse”, specify the firmware file, for example U30_2.52_07_08_2021.signed.flash and click “Flash” to start the update process. Upon completion, you will need to reboot the server, this can also be done from iLO by clicking on the icon in the upper right corner.