Quote Originally Posted by Firestorm
but I don’t know how to make my computer type in Japanese,
You need get a computer from Japan.

Just kidding. It depends on what operating system you're running.
Here are some links:
For Microsoft Windows PC
Fedora 12 (Linux)
Mac OS X
Unix

Quote Originally Posted by Firestorm
could someone tell me how to type in Hiragana, Katakana and Kanji?
May vary depending on Operating System, but on Windows once you've enabled the language bar you should see it on the bottom right of your monitor, near the clock. It should be a small blue square with "EN" (English) written in it. Right click and maximise it and the language toolbar should be on the top of your screen. You can then use your mouse and click on it which will produce a drop down menu with the available languages you've installed (e.g. English (Australia) / Japanese). Choose Japanese. Alternatively you can just hit ALT + SHIFT to toggle between languages (which is very useful when switching between languages in the middle of typing!).

Once you've selected Japanese it's default in Roomaji, which means you can still type like in English. The third option from the left should be "Input Method". Select this and choose either "Hiragana" or "Full-width Katakana."

Let's start with typing in Hiragana and Kanji first. Once you've selected "Hiragana" just type in Japanese Roomaji. But remember that ん is typed as "NN" (double-N). Also remember to type particles as they are in Roomaji, so for example the particle-wa is "HA" and particle-e is "HE".

So if you want to type "Konnichi wa" you neet to change the input method to Hiragana and type "K O N N I C H I H A" then hit enter to confirm.
So you will get this:
KO = こ
NN = ん
NI = に
CHI = ち
HA = は
Result----------> こんにちは

To type in Kanji you do the same thing but hit SPACE to see options for Kanji. So again, for "Konnichi wa" I would type KONNICHIHA and get こんにちは, but before hitting enter I hit SPACE. At first the computer will simply highlight こんにちは in blue, so hit space again and a drop down menu will appear. Select the first option and hit enter and こんにちは will instantly convert to 今日は.

In some cases there may be multiple Kanji options. For example if I type "SEI" (せい) and hit SPACE, I will see pages and pages of options! You simply scroll down and select which one you want. Usually the most commonly used Kanji are listed first. The list gets shorter if you can type in more syllables, e.g. if I type GAKUSEI (がくせい) and hit enter, there's only 3 options. Sometimes none of the options are what you want in which case you'll have to do each part separately and scroll through the pages until you find the Kanji you want. You can also just hit the number next to the kanji you want instead of using your mouse (I usually find hot keys faster than mousing).

Some useful short cuts:
CHI can be inputted as "TI"
TSU can be inputted as "TU"
SHI can be inputted as "SI"

Also:
For this JI (ぢ) you must type "DI"
For particle O (を) you must type "WO"
For this ZU (づ) you must type "DU"
To make anything half size type "X" in front of it. e.g. A = あ, but XA = ぁ

Typing in Katakana works the same way as typing in Kanji, but it won't usually convert words to Kanji since Katakana is principally used for writing foreign words. So if I want to write "Optimus Prime" I would type "O-PU-TE-XI-MA-SU PU-RA-I-MU" which gives me this: オプティマス プライム

Quote Originally Posted by Firestorm
Also when someone says to you "Hisashiburidesne" what do you answer with?
That's like "Long time no see," so you'd just reply with something appropriate... like maybe, 「ええ、そうですね。おひさしぶりですね」