How to add text in a picture in photoshop without loosing its quality?

I'm a beginner in photography and in photoshop as well.
i have taken a photo with a nikon camera 14.2 MP and i only want to add a text on it (no other editing process, just text) but when i save the photo it reduces the quality. What is the best image format to use?

here is the photo i have taken

Putting text on it does not reduce the quality. You are doing something wrong in PS. Open the file, ad the text, flatten the image and save it.