if you have installed qtlockscreen then the folder for the .ini file will be /home/user/.config/sakya and the images should be in /opt/qtlockscreen/default (not sure about the default folder but the rest is accurate) you will find the default images in this folder . now the thing is ammyt's images folder . ask him or if he has mentioned it already , do as he says . but the .ini file will be in /home/user/.config/sakya make sure you make a copy of your .ini file in case you wanted to switch back