Help in writing a letter.

Good day to all,

I've heard and read that there certain proper ways of writing a formal letter, as to what season it is, and what is the purpose of the letter, if it is the start of a chain of mails, or just a reply.
But let's just say that I need to write a letter for just inquiring about a job opportunity online. The listing was found in a Japanese website, and the only method of contact for any questions is by email. So what would be a good/proper way to start this letter.
If someone could actually help me out in writing the whole letter, that would even be great.

To give you an idea, what this/these letter be for. I've been working for almost 10 years as a blue-collar employee here in japan,
and (for reasons) am now trying to start a career in IT (networking field). And this/these letters would help be get to the stepping stones. Any help would be greatly appreciated.

P.S. I have only daily-conversation to slightly intermediate skills in Japanese,

Cheers.
Jon

I suggest you look at sites for writing business letters/emails, or get a book on same. (Often 例文 + メール + appropriate keywords will get you what you need). For example : here's one and here's another.

The full-on formal style isn't necessary in these cases (as you'll see)