New player, got a few questions

Well, I was wondering about playing different chords. The song I'm learning is 'Save Tonight' by Eagle-Eye Cherry, and one of the chords (Am) doesn't use all the strings. All but the 6th string are used (at least says the book I've learned 'em from), so I wondered when you're strumming, do you have to learn to avoid the 6th string so it doesn't ruin the chord, or can you play it anyway? I'm just getting the hang of playing, so please pardon all the lame questions. Any help is greatly appreciated!

no you better don't play it , you should try to strum only the 5 strings you need , you can also try to mute the 6th string with your thumb , with other chords you can mute it with other fingers you use for the chord , but you should try to strum as accurately as possible , so no more strings than needed ...

Schweet! Thanks a lot, it helped a load, believe it or not.