New theme and new wallpaper

[AC Question]

Please, I'm trying to change the freakin' stock theme and wallpaper that came with the smartphone (an L2 G2-Mini with whatever version of Android installed). I don't want to install any app to do it, I don't want to even delete the original crappy stock wallpaper/theme. I just want to be able to upload my own 2 files (jpg/jpeg, that will "serve" as my new theme/wallpaper) to the proper directories in either the phone internal storage / SD card devices (using simple Windows Explorer MOVE mouse sliding command, as regular windows users do). So I need to know the exact location (folder) of the original theme/wallpeper. Hope I've been clear enough and that somebody knows how to help in such a simple task.

 

[UJ95x]

You don't need to delete the wallpaper you are currently using to change it. It will just be replaced. You can save the file on your phone, go to the gallery and hit the menu button. From there hit set as and it will likely ask you to crop it so it can be set as the wallpaper.
As far as the theme, you will likely need a third party app for that. I know LG has a themes store but I am not sure if that is available by default or if it;s even an option on the G2 Mini.