root folder?

i've just updated to 3.90 m33 now i want to install the 1.50 kernall and they say to put the official 1.50 eboot update into my root folder and call it 150.pbp Well i guess i did something wrong because it says i dont have the update there maybe i missunderstood root if they say to put it in root folder do they mean MP_Root ??? or do i need to make a folder at PSP/GAME/root ??

Root is the folder before you go into 'PSP' it is "F:/Root/PSP/GAME/" Substitute F for whatever your psp USB drive is.