Katakana works very similarly to hiragana however katakana is used for words that come from languages other than Japanese and Chinese since Chinese words are written in kanji. A good example of when to use katakana is when an English word is being written in Japanese. Katakana like hiragana also has a chart and can easily be memorized using it.
N | W | R | Y | M | H | N | T | S | K | ||
ン(n) | ワ | ラ | ヤ | マ | ハ | ナ | タ | サ | カ | ア | A |
リ | ミ | ヒ | ニ | チ(chi) | シ(shi) | キ | イ | I | |||
ル | ユ | ム | フ(fu) | ヌ | ツ(tsu) | ス | キ | ウ | U | ||
レ | メ | ヘ | ネ | テ | セ | ケ | エ | E | |||
ヲ | ロ | ヨ | モ | ホ | ノ | ト | ソ | コ | オ | O |
The muddied sounds for katakana work the same way as the hiragana sounds do which makes them pretty easy to learn.
P | B | D | Z | G | |
パ | バ | ダ | ザ | ガ | A |
ピ | ビ | ヂ(ji) | ジ(ji) | ギ | I |
プ | ブ | ヅ(dzu) | ズ | グ | U |
ペ | ベ | デ | ゼ | ゲ | E |
ポ | ボ | ド | ゾ | ゴ | O |