how does this kanji fit in?

[rs1919]

Today I attempted to expand my japanese knowledge . I understand that it has the on and kun reading... however I need some reasoning behind why sometimes the kanji does not match the kun and on readings all the time.. Like this for example

The Word in kanji:　日本
The Word in hiragana: にほん

I know this means Japan... what I don't get is the way it's spelled in hiragana versus kanji. Like just for 日 (に?) because the 'on' and 'kun' readings don't match up. However 本 (ほん) does match.

Am I missing a important point to kanji? I only started today so I hope this is not to dumb of a question

[richvh]

First of all, don't sweat irregular readings; learn how the word is read, which is more important than matching up on or kun readings.

In this case, the original reading にっぽん (にち contracted with ほん to give にっぽん) got changed にほん (as most p-sounds changed to h-sounds did in the course of Japanese phonetic drift), with にっぽん being retained for formal occasions.

[Mike Cash]

You're in for lots of fun.

Yesterday down at the docks I looked over at the truck next to mine and read the company name. At first glance I thought it was 大平　（おおひら）. Then I looked more closely and noticed that I had missed a "dot". It was actually 太平　（たいへい）.

Then you have such fun things as:

東　（ひがし）
東海　（とうかい）
東海運　（あずまかいうん）

Never a dull moment when reading Japanese.