modeling - how to refine the mesh in some parts of 3D-Model

I have created a 3D model. I want to refine the mesh at some parts (like the picture shows) of 3D model. I want to increase the number of meshes in the red circle area. Waht should I do? Thanks a lot.

modeling - how to refine the mesh in some parts of 3D-Model? - Blender Stack Exchange