No problem. All this is saying is that the six NOT gates are independent--or "seperate" from each other. The second part means that you'll need pull-up resistors (or pull-down, if you want) to keep the input from floating randomly if nothing else is connected to it. The last 2 sentences aren't too important for now.
Here's a cutaway drawing:
**broken link removed**
...Here, if you only wanted to use 1 NOT gate, you could use pin 1 as the input and pin 2 as the output. (It doesn't have to be pins 1 and 2, we could just as easily use 3 and 4, 5 and 6, 8 and 9, etc.). This way, the logic level at pin 2 will always be the opposite of pin 1.
The other 5 NOT gates can be used in the same manner; or can ignore them (remember they're independent).