I'm off line soon, so I'll give you what info I can:
your nand2tetris
Folder (that's been extracted from your zip file) (which you might have done already) should contain two
Folders Tools and Projects. If you open Tools it should look a bit like this:
![](http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/file/n4035432/filesInTools.png)
I don't know about your operating system, but mine alows me to go to the command line/terminal by clicking on the File button:
![](http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/file/n4035432/croppedfilemenu.png)
click on Open in Terminal
you should then be able to do the chmod commands of CPUEmulator.sh as mentioned before on my post at 12.19 today
Good luck !