Image and image

Hi, I’m Francesca and I’m trying to use your wonderful plugin for my wedding website.
I thought it would be a nice touch if when you hover the mouse/curser over a picture, it switches to a second photo, maybe of that person doing something silly. Just to make it a bit more personal and fun.
Among the general effects, there is a particular one that I fell in love with: it is the 1st one of general effects 3. I love that there is this rounded picture that moves to the right giving to another rounded picture.
My issue: I’m able to substitute the main picture but I’m having a really really hard time in editing the feaure image: everytime, even if I add the feature picture that I want, a round purple circle appears and there is no way to see the feature picture. Please help.
I also tried the 3rd general effects 3, the template that has a picture of a lion. In this case I was able to substitute both pictures: the main one and the feature one as well.
You could ask yourself “what’s the problem, then?”.
And you would be absolutely right.
Though the fact is that I would like to have rounded pictures and not squared pictures (as it happens in general effects 3 number 3rd).
I would be very grateful if you could help me with the 1st template of general effects 3: 2 pictures.
Best
Francesca