How to create New Folder under Places on Mac?

i am not sure what you mean?

could you be more specific?

you should be able to add a folder under the file drop menu.

sometimes depending on the program theres a + symbol int he bottom left corner that will add a folder, i would like to know what you are tryign to add it to?

and sometimes you can just make a folder and drag it where you want it

 

Just drag any folder from the right side of the window in Finder to the Places area on the left sidebar. Everything under Places is just an alias.