Hello and welcome from NZ.
The TuneECU is not hard to use once you get the cable. Only thing I found you need to be careful with when setting it up is Windows sometimes tries to install the incorrect driver for the cable onto your computer trying and "help" you with the installation, easily fixed though.
Once you've got the program go to the TomHamburg site and have a read of the instructions and unless you are completely confident with what you are adjusting don't do anything and ask the site. Ive found there are many clever people here more than willing to help.