I am modeling a picture frame. I would like to have a rounded profile instead of a straight one. I divided faces than I want to bend with loop cut tool. but I have no idea.
You could use a custom bevel profile.
I started with a cube, inset the front and back face, and bridged the edge loops to create a frame.
Select one edge loop and create a bevel with Ctrl + B.
Once you create a bevel, you can open the panel in the bottom left to modify your last action. Bump up the number of segments and select Custom profile. You can model your bevel using the curve provided.
You could create a right angle and bevel it with CtrlB (the options are in the Operator box):
If you have already given your angle a bevel like this one:
You can select a central edge, enable the Proportional Editing option, choose its Smooth falloff option, make sure that the radius is small enough (mouse scroll wheel) and move the edge on the X axis:
Here I give an answer that might also help for this kind of object.