Adding new pictures to lock screen choice

I have five basic lock screen pictures and would like to add some more and even make it so that it changes pictures for each time I boot up.

Is this possible?

Thanks NMI I can see how to change to slide show but there are only five basic pictures for it I was just wondering how to add to that collection just as my background pic is changed but I don't know whwere they are stored either or how to add to them .

The lock screen I suppose is not that important but I would like to get some more for the background collection. I have some stored in Pictures but if I set it to pictures it will only show one it will not scroll through them all or at least the ones I have added.

Thanks NMI but my settings will not let me choose anything but the default ones and I have tried to save a heap of pics I like in Picture Saved Pictures Camera roll etc but like I say the option to choose a folder is not there.

Yes mate I have tried that and it just says you need more than one picture in the folder never mind as long as my background keeps going it will be ok.