Don't worry too much. In order to learn Japanese, you will need to read and write a lot. In some time you will get used to both, hiragana and katakana. Since hiragana is used much more, you will notice that katakana requires more time, but seriously, do not worry too much and go ahead studying even if you need to look from time to time at the kana charts.

Look up some words in a Japanese-English dictionary that use Katakana and try to memorize vocabulary using the ones you are studying currently. Also, image association is very useful for memorizing the shape of the characters, so if you can find some mnemonics online that associates the shape and sound of a character with a particular image, you will memorize much more easily. Alternatively, you can create the mnemonics yourself, which would make it extra easy for you to remember.