There's a couple of ways you can use bat guano to fertilize your soil..
- First, is to simply mix it in the soil.
- Second, is to make a mix of soil and guano, and pour a tiny layer on top of the soil. (This is generally called top dressing, and is mostly used for lawns if my memory serves me right.)
-. Third is to make a liquid fertilizer. (Usually called "tea")
What method you should use and how much guano, depends on your preference and need. So I'd google a little about the 3 things before you start.