As I recall there is a painting object that you can use. But what I've done is this:
place a wall that is as wide, deep, and high as the frame (say 3' x 4' x 1") Then place a niche into the wall that is the size of the picture and 1/2" deep (so in this case 2'-8" x 3'-8" x 1/2"). Then set the niche tool to a material that is your painting. Align the material in 3D and you're set.
To make the material:
create a material that has the painting as a jpg. Set the jpg size to your niche size (2'-8" x 3'-8").
A little complex, but really versatile and fast once you've done it once. And it uses skills you should learn regardless (niche, align 3d texture, and material creation). If you use a generic material to represent 'painting' (aged copper for instance), then you can skip the material making and aligning.