Normally, your deli/charcuterie store will slice the prosciutto for you, either manually or with a meat slicer (more often).
The melon, is thinly sliced manually, just pick a ripe melon, halve it and slice it up and remove the rind.
Depending on the thickness of the slices, you will be able to make fancy folds like in the picture, or maybe not, then you will just have nice slices.
Melon and Prosciutto is a simple dish where ingredients is more important than presentation.
i personally, just slice the melon in wedges and drape the ham over it, or roll the ham around pieces of melon.