When it said to count to 1000 as fast as I can can count to 100 because i can't count to 1000?

No, that is not good enough. But don't worry. You will be able to do it when you're a little bit older.

For now, though, you could count to 100, and make a tick on a sheet of paper. Start again and when you get to 100 make another tick on the paper. And keep doing that. When you have ten ticks on the paper you have counted the same amount of numbers as counting to a thousand.