I am following this tutorial link
There three types of screens
xlarge screens are at least 960dp x 720dp
large screens are at least 640dp x 480dp
normal screens are at least 470dp x 320dp
small screens are at least 426dp x 320dp
But there are three folders
drawabale-hdpi
drawabale-mdpi
drawabale-ldpi
I placed images of xlarge in hdpi that of large in mdpi and that of normal in ldpi but where to place the images of small screens? Sorry for bad english