you either have your UAC settings on which prevents dragging and dropping, to turn this off go into control panel and search for USER ACCOUNT CONTROL settings, change it so it never notifys. you will need to restart your computer. or you can simply right click in the USB Tool (the white part on the right) and click inject, find the file and press ok.. say yes to overwrite.
i rigth cliked the save and clicked send to device and its saying there isnt enuf space,even tho i cleared the drive
open the USB in 360revs USB Explorer, Click on File > Open. Once its loaded, Click on USB > Data > Content > E0000 etc (your profile) > Minecraft > 00000001. Then in the white box with you save right click, and select inject. double click the modded save. and then overwrite when the box pops up.
i had to have done something wrong while downloading,it wont let me click data,it just lights up blue
once downloaded, open the file and there will be a username and password on the left, send me both in a private message.