I am trying to learn scripts but I am not really doing well.

I want to create a sheet with currency exchange rates that updates every 5 minutes and gets sent automatically to my e-mail IF certain rates are met.

First step:

I created an IMPORTHTML formula as per the exact instructions mentioned on Geckoboards website, which I can't post a link of here due to restrictions (urgh...)

My formula looks like this and it retrieves the first table, but it does not update it automatically.

Second step:

I need a script that updates this formula automatically every 5 minutes. In order to achieve this, I followed the steps on the same page on Geckoboard, but the script does not seem to work. While the Google Sheets is "updated" every 5 minutes, the numbers in the table are not. Can someone explain what I've done wrong and what I should do instead? Please be detailed as I am a new to this..hehe

1) Open script editor
2) function getData
queryString = Math.random();

Sorry, can't write the full script here as it gets denied..

3) Set it to run every 5 minutes.

Third step:

Is there a good way (script? free and secure add-on?) to send "e-mail alerts" if certain exchange rates change X %? What I need is an alert-based send out, not continuous broadcasts. Any advice on how I would achieve this?

Many thanks