how to boot uefi from partition

greets! yrs ago I thought BIOS was mysterious; I didn't anticipate UEFI! was travelling, my SSD collapsed - dead - and I had to get another and get Linux installed fast. put Kubuntu on; back home added tde. I just resized the partition and added another ext4 with exegnu installed but I installed the loader to the partition, fearing to touch /boot/efi. so there's boot/efi on sda1, kubuntu on sda2 and exegnu on sda3. there's some crap in my efi because of other misadventures but the important thing now is I can boot into kubuntu, what do I do so I can put into exegnu also? is it simply a matter of grub-install? other magic? my ultimate goal is to remove kubuntu and install Windows 7 with exegnu as the default boot. f. -- Felmon Davis "Home, Sweet Home" must surely have been written by a bachelor. -- Samuel Butler