When restarting the device you should be able to press F12 rapidly while it is turning on to get into a one-time boot menu and select your Windows 11 Install drive, otherwise you may need to press F2 rapidly to get into the BIOS and select boot options from there.
If you need more help installing Windows 11, Framework have a guide here:
If you need more guidance on the BIOS there is a community post here: