Japanese is written in three script systems, hiragana, katakana, and kanji. If you ever wish to be able to read real Japanese, it is essential that you dedicate some time to learn all 92 kana, and then start working on acquiring as much Kanji as possible. It's beyond my ability to teach you kanji, but I will be pointing you along the way in the right direction. The most critical thing to get out of the way first, though, is hiragana. These 46 characters will allow you to phonetically write any Japanese word. Further, we will get to Katakana, which is used to write loanwords that Japanese has integrated from other languages (i.e. pasocon, compyuuta, etc.)
Vowels
If you speak Spanish, you already know all the sounds of Japanese, except for "tsu". Say "cats" and then and "oo" at the end, that will give you the proper sound for "'tsu"
The vowels are consistent in Japanese, except for "shi", "tsu" and "su", where sometimes you don't hear the vowel at all: Watashi ha Juan desu. sounds like: Watashi wa Juan dess.
Basic Hiragana
Dakuten Kana
There are small marks that will alter the pronunciation of the kana to make other sounds available. Below you will see these. The two dashes are commonly called "ten-ten", the little circle is called "maru".
Glides
Hyaku, byaku, byouki, all of these are pronounce with a glide, a small "ya", "yu", or "yo" is used in addition to the initial "i" sequence kana.
* Rarely used. Sound the same as the "J" sequence. (ja, ju, jo)