You’ll want to aviod foods that are salty or spicy. So generally you’ll want foods like:
oatmeal
bananas
bread or toast
potatoes
Rice is also a good choice.
Remember that if your diarrhea persists you need to go and see your doctor. There could be a deeper problem that you need to solve. The foods listed above are just good guidelines on what to eat but they are not a cure for any issues that may be causing your diarrhea.