I found all the Al Bhed primers, but I'm having a lot of difficulty with the treasure hunt in the Calm Lands. The first stone tells me to walk 49 paces down, then 7 over. I find that one. Then it tells me 20 down and 20 over. I find that one. Then the next one says 16 right and 4 right. I have tried everything but cannot find anything when I follow these. I tried walking and running, pressing X in all over the field, I still can't find where it's pointing me to. Help?

Walkthroughs explain this as if there is supposed to be something there and I can't find a video showing this. It just leads me to an empty part of the map. No stones, just grass.

Are you sure you're doing the last one correctly? A quick google search to check and it says:

16 Down, 4 Right.

Not: 16 Right, 4 Right.

It should lead to some spiral on the ground which contains your final clue/direction. The result being something that tells you a password for the airship. (I've spoiler-blocked it if you don't want to accidentally see but I haven't actually said what the result is)

Since you've done the previous two parts correctly, I'll assume you know this, but I'll mention it anyway. Paces refer to Tidus walking so make sure you are walking (I think holding one of the face buttons, O maybe, keeps Tidus walking instead of running).

This one annoyed the heck out of me on its first release and I wound up looking up spoilers for the answer. I recommend you do the same. It's not worth the hassle in the Calm Lands.