You would either need to get that album of trx signed up by a label of some sort so that they could then instigate putting it onto iTunes, or you can try and find an online distributor who will put your music across lots of download sites for a cut of any monies made from sales.
The problem is distributors tend not to like individual artists approaching them for a distribution deal. If you were a label and had a significnt body of work then they might be more interested as it will generate more funds for them.
I would suggest that putting your music onto iTunes is not necessarily the best option anyway as you'd just be a drop in the ocean. It is more likely that you will gather more attention on the smaller mp3 download sites that cater for more specific tastes/genres. Have a look around for music/mp3 download sites that distribute a similar type of music to you and perhaps try approaching them.
Ususally they also don't like individual artists approaching them, but who's to say your not a label owner who's trying to push this great new artist called 'Watercolour's music out to the masses. [sometimes you have to be a little creative with the truth].
hope that helps a little.