Bealzebub is a well respected regular in this forum and has taken the time to give a pretty comprehensive answer - you're lucky that He/She got to you before I did as I would normally have deleted your question immediately - here is why...
The 'How do I get upgraded?' question is often asked by newbies who have not used the forum search facility, or read the FAQ or even just a few posts to get familiar with the forum tone.
Once in place, word gets out, and the forum can easily drown in similar threads.
Lastly, many of the most stalwart and frequent contributors to this forum are people who travel extensively, and spend large amounts of money with Airlines in First/Business class. 'How do I get upgraded?' translates as 'How do I get something for free that others are dumb enough to pay for?'. It's just possible that those same folk that pay might not appreciate this question? The answer is always the same - the best way to get an upgrade is to pay for it.