The first character is "Ah." Like the Hiragana alphabet, the Katakana alphabet can be arranged in a 5-column chart with the first row of 5 characters being the vowels: "Ah, I, U, Eh, Oh." (A I U E O)
"Ah" is pronounced like the end of the English word "Saw."
The next we need to learn is "I" which is pronounced like "EEE" You could pronounce it like the English letter "E."
Next we have, "U" which is pronounced like "Ooh." It sounds like the "u" in "Glue."
Now we have "E" which sounds like the "ay" in "Say."
Here is the final letter, "Oh." It sounds just like the word "Oh."
That's it! You now know the first 5 letters of the Katakana Alphabet. Check out my other articles if you'd like to know more about Japan's other alphabet, Hiragana. Remember, Katakana is used primarily for writing foreign words. Names of westerners are typically written with this alphabet.