Newer versions of Paintshop Pro (and any other half decent graphics app) will have a useful feature to create seamless tiles from images. What did you use to make this?
I have to say, it doesn't look much like sand. Sand is very rarely that yellow, although it obviously does vary a lot too. Also, I'd say there's too much solid yellow - it looks a bit like a lump of yellow "stuff" with bits of brown sprinkled on top. What distance is it meant to be viewing the sand from?
I used the "create seamless tile" tool in PSP. The "clone brush" could have been used instead.
Since you're using crappy paint (WHY are you using crappy paint again? Didn't you read my "Pixel Art for Total Newbies" article ) here's what you could try;
Firstly, start off making the image quite a bit bigger than you want the eventual tile to be.
Then, pick an area the size of your tile, that looks free from too many obvious dark/light/patterned areas.
Now, try copying and pasting the tile a few times to see how it looks tiled.
Look for areas that obviously repeat. Copy small sections form your original image, and paste them over these areas. It'll probably look better if you make the selections freehand rather than in rectangles.
See how it looks tiled again.
Repeat the last few steps until it looks ok (or worse than when it started, in which case start over).
Seriously though, use something better than Paint (in other words, anything other than Paint). It really does suck.