Newbie Espruino Wifi createServer Problem?

when I hold the button down an add power the green light goes on, then the red light flashes, then they both go off.

After about 3 seconds? I think you're just holding down the button for too long. Plug it in with the button held down, then release the button as soon as the green LED is lit.

If you hold down the button for > 3 seconds it continues to boot Espruino, but without loading any of the saved code (it's a recovery thing in case you saved code that caused problems).

Once I've uploaded my software the Espruino should run it without the computer connected I assume?

Usually your upload goes into RAM. To save to flash you'll want to just type save() on the left-hand side after uploading (but remove the call to onInit() that you put at the end of your code).