I need a magnifying glass effect like described below.
Here is an instruction for Photoshop:
Make a new layer on top of the background, then make a circular selection (hold down shift to make sure it is a perfect circle) and fill it with any color that you want. Set the fill % in the layers palette to 0%. Go into the layer FX and add a stroke (black) and inner glow (white). Keeping the circle selected, move to the background layer and hit ctrl+c (copy). Make a new layer above the background but below the magnifying glass, paste the copied part, line it up pretty well, hit ctrl+t (free transform) then scale it while pressing both shift (to keep it proportional) and alt (to keep the center stationary). Ctrl+click the magnifying glass layer's icon in the layer palette (the one you made in step 1, stroked in step 3, etc.) and then hit Ctrl+Shift+i to invert the selection. With the zoomed content layer selected (from step 5,) hit delete. Bring up the FX for the zoomed content layer and put a fuzzy drop shadow on it.
It should look like the attachment. Important, we should be able to modify the project, adding our own image etc. Ready design must be editable in Pixelmator, not only in Photoshop.