Compound unvoiced katakana
The next batch of katakana you need to learn are composed entirely of characters you're already seen - and if you know hiragana, then there's doubly nothing to fear - so don't panic. As with the hiragana, each of the following syllables is written with a full-sized katakana (ending in an i vowel sound, such as ki, shi, chi, etc) followed by a small ya, yu or yo. Again, move your mouse over the characters to see the romanized form, and all should become clear.

So, as you can see, hi plus a small ya is not hiya (two syllables, sounds like it should be a kung-fu shout) but actually hya, a single syllable. Shi plus small yu is shu, not shiyu; chi plus small yo is cho, not chiyo, and so on. Get really good at recognising ya, yu and yo, and these syllables will be easy to pick up.