Putting in a rock garden is fairly easy especially after the first few steps. The garden can be as big or small as you want and be placed anywhere in the landscape where you want it. Maybe in a dull corner of the yard.
First, take a hose and use it as an outline of what you want the outer edge of the rock garden to look like. The till or spade the grass or weeds under (you can use a Roundup type of herbicide to kill the plants before tilling up). Place good soil on top giving the rock garden an elevation to it, maybe a few inches. There is a layering method by placing old newspaper on the ground before adding soil to smother the grass.
You can also lay down landscape fabric after mounding with soil to keep the weed seeds from growing or making them easy to pull out. Just cut an X in the fabric to plant your desirable plants.
Now for the rocks, feel free to be creative with the texture and color of the stones. Make sure you have enough to cover the area. This is where a rock specimen like rose quartz or a stone-looking fountain adds interest drawing your attention toward the area.
Now add your plants. Tough low growing perennials like creeping phlox or sedums do well in these areas. Keep away from annuals that need planting every year.