The first thing you need to do is to launch the Ext4 Unpacker software and then you need to select the open button.
Select the system.img you want to extract.
Press the "Save as EXT4" button.
Select where you want to save the .ext4 file and enter a name with the extension .ext4, then press Save.
Wait while the ext4 image is being unpacked.
Launch the ext2explore software as a Administrator (Do that or it wont work!) and then select File then Open Image.
Select the file you saved earlier with Ext4 Unpacked software and then select "Open".
Now highlight the file you just have imported in EXT2Explore and then press the "Save" button.
Select where you want the unpacked system files to be placed.
After that is done just go to the folder and voila! The android system files should be in the folder.