Hi Turtle Rider, the idea behind meditation, from what I know, is not to clear your mind from thoughts, sort of. When you're meditating, and thoughts come up, its natural. If they didn't, you'd be a robot or something.

Anyway, there's a lot of ways to meditate, but from what I know about mindfulness meditation, the idea is to focus your attention on something, like your breath (or an image, or sound), and know that your mind will wander, and that's ok. That's part of meditating. When your mind wanders and you first notice that you are getting wrapped up in thought, gently notice this, and bring your attention back to your focus. When your mind wanders again (and again, and again, and again), each time you notice, gently bring your attention back to your focus.

I hope this helps.