what is the quickest way to learn how to write a computer application?

[VE9A]

My advice is to start off with basic scripting languages spend about 4-7 weeks on those
til u know them by heart, javascript &/or php with html an CSS would be a good start.
W3schools website has tutorials for this that should get you to an industry standard level
or at least ready to take on advanced topics within these subjects.
My reasoning for suggesting these is that scripting languages were designed to build basic apps with the minimum amount of code, it will allow u to understand the basic principles of programming such as loops, arrays, an conditional clauses with the minimum amount of coding involved.

Once you've mastered these basic concept u can move on to more advanced scripting languages such as C# and finally go to a fully fledged language such as C++

the most important thing is to have fun an draw on knowledge from multiple sources