How do I use this Korean keyboard?
Type on your normal keyboard and each key types the Korean letter shown on that key on the on-screen keyboard: for example, gksrmf gives 한글. The letters join into syllable blocks as you type, so ㅎ + ㅏ + ㄴ gives 한. You can also click or tap the keys on the on-screen keyboard. When you've finished, press Copy to copy your text.
Which keys give which letters?
The keyboard uses the standard 2-beolsik (두벌식) layout: consonants are on the left of the keyboard and vowels on the right. For example, Q is ㅂ, R is ㄱ, A is ㅁ, K is ㅏ and L is ㅣ.
How do I type double consonants like ㄲ or ㅃ?
Hold Shift: Shift+Q gives ㅃ, Shift+W ㅉ, Shift+E ㄸ, Shift+R ㄲ and Shift+T ㅆ. Shift+O and Shift+P give ㅒ and ㅖ. Shift with any other key types its usual letter.
How do I type vowels like ㅘ or ㅢ?
Type their two parts one after the other: ㅗ + ㅏ gives ㅘ, ㅜ + ㅓ gives ㅝ and ㅡ + ㅣ gives ㅢ. Final consonant clusters work the same way, so 다 + ㄹ + ㄱ gives 닭.