Kerning is one of those things that when done properly, you don’t notice. The text is easy to read, it’s easy on the eyes, and it's comfortable. It’s when the kerning is done poorly that suddenly the text is awkward and sloppy. It can even take on a totally new meaning.
To explain this better, I think it's easier to show you examples. (I always like visual examples!)
Luckily, most software today, even ones not specifically for design, have some sort of kerning option. In the design world, standards like Adobe products have easy kerning options and shortcuts built in to make it a quick and simple fix. Other more cumbersome programs like Word and Publisher have ways to do this if you start digging around in the formatting and fonts tabs.
So, what IS good kerning? It’s when the letters fit together with an even, comfortable space around them. The trick is that with characters that have round shapes and diagonal lines, they aren’t going to automatically fit and look good. So it’s the designer’s job to fix that. In my example, I’ve typed a common word, ACTIVE. In the first frame, it’s shown exactly how it was typed. In the second, I’ve adjusted for the slant of the A, the curve of the C, and the slant of the V. Can you see the difference?