How do install windows 8 on ssd?

I have an acer which came with pre installed windows 8 on hdd.my laptop also had a 20 gb ssd.i want to install windows 8 on ssd but have no idea how to do that.note that laptop didnt come with a windows disk.even if i manage to make a bootable thumbdrive,i'll not be having a product key of windows 8(as it is present in bios for windows 8).i dont have any idea what will affect my bios,so kindly guide me about that also.thanks