ok first make a folder on your desktop, then open the winrar file, right click on the folder inside winrar and select "extract to specified folder" then select the folder you just made. then you should be able to use the folders fine. (sorry for the delay, been busy)
well first you gotta right click on the folder you want to change and go to properties, then go to customize and click "change icon". then click browse and locate where you put the osomatsu files and choose the one you want.
I apologize I'm not that good at instructions, but if you need any further clarification there are tons of tutorials on google that should help