Here is the resource hacker I used, it is free Anolis Resourcer - Resource Hacker Software - Anolis
The ExploreFrame.dll is in C:\Windows\System32 and if you are using 64-bit it will also be in C:\Windows\SysWOW64 so you would need to edit both.
Here are the image numbers for the button's
280 - frame
577 - default
578 - hover
579 - disable
581 - pressed
These are if you have your DPI set at 100% if you have it set higher you will have to do the other buttons.
Open the ExploreFrame.dll (Use a copy of the original so you do not corrupt the original) click on the + sign where it says Bitmap scroll down to in this example 577 click on the + sign then click on 1033 then click on the Export button.
Save that bitmap to your desktop that you will need a image editor to edit the image to your liking.
After you have edited the bitmap or if you already have a set of buttons that you will need to click on the Replace button.
Click on the Browse button.
Navigate to the button that you just edited or if you have a set of buttons and select it and then click Open.
Click the Load button then click the OK button.
Repeat the above steps until you have all the bitmaps changed.
Click on File then Save, you will not see the changes in the resource hacker window unless you close the program and then open it back up again and click on the images #and then you can see the changes.