Structuring a Script

The first thing I want to make clear is that I am not a writer, I have attempted to start writing a script or two but have not had much luck so far. The first think I really need to know, if I am to research into scripting, is how you might structure a film script.
The following information was taken from a web page I found while I was trying to find out how I could improve my scripts.
On this web page they believe that any script can be written if you stick to the following four point structure:
· “A main character who is driven towards achieving a goal
· An opposition to your main character who will hold your main character back from achieving their goal
· A fight (literal or metaphorical) between your main character and their opposition
· An ending which answers the questions "Can the main character achieve his goal?"
(http://www.filmscriptwriting.com/storystructure.html)
I have found that this was not a very useful piece of advice as I disagree in many of the points. The first of the points I do not agree with is the second point. On this web page they believe that you must have “an opposition to your main character”. If this is the case then a lot of films would have failed, in Clerks there is no opposition to speak of there are a few confrontations but no actual opposition. “Clerks was a highly successful film and lacked an opposition.
I also do not believe that you must have “An ending which answers the questions "Can the main character achieve his goal?" An example of a film which has done well without this aspect is “The Italian Job”, which ends with the thieves stuck hanging off a cliff with a large amount of gold in the back, the film ends there with no conclusion as to whether of not they got out of that situation.