From your 'My Hub' page (please see below)
If you hit the 'Menu' icon in the top right...
and select 'Contacts' from the options
You then select the client profile
You can then click 'Progress Photo's' from the list under that client's profile picture
where you will have the option to 'Upload Progress Photo'.
Simply click the upload file icon
Select the pics and click the 'Upload' button.