<p>Do I talk about the past or the future?</p>
<p>Definitely talk about the future and what you want to do in and after graduate school. If your C’s are from early in your undergraduate career, no need to say anything. If they are because of a bad semester due to some outside issues, you might want to say a few words but not belabor the issue. If your C’s are outside your major, no need to explain.</p>
<p>A couple of C’s aren’t the end of the world. I wouldn’t try to explain them at all. It’s not really necessary unless you did pretty bad on more than just two classes. If you’re posting here looking for an explanation and don’t have a real one, you’ll probably just come off as someone who makes excuses. Believe me, I’m sure the admissions committees have heard plenty of excuses before.</p>