I'm trying to do a cosmetic bottle in blender but i don't how to do this thing in the image. How to do this round edge on the cap. Can anyone help me?
Add a cylinder with 16 subdivisions. Add edge loops Ctrl+R to define the indentation position. Select the faces representing the indentation and press I,B (to enable Boundary mode). Repeat it twice (to create the extra edge loops for subsurf creasing). Extrude it inwards (E), then inset again as before.
To answer to Kosmani's question here, which is about a slightly different lid:
You can begin with a 32 vertex cylinder and 16/8 vertex sphere that you'll use as a boolean object:
Apply the Boolean, add some horizontal edges with the knife tool:
Rearrange the topology a bit, give your object a Solidify modifier:
Apply the Solidify, bevel the edges in order to sharpen when you'll give your object a Subdivision Surface modifier: