As is the way with Linux, there are many applications out there to allow you to manipulate image files. The most well known and widely used is called GIMP. It has a similar feature set as Adobe PhotoShop Elements, for manipulating images. Personally, I don't believe it's as good as the Adobe product, but it is free! You can do pretty much the same things (-only with less control) but I do find it less intuitive to use and not quite as flexible (-but, then, I'm no expert).
If you're familiar with Adobe PhotoShop Elements, then you will not take too long to convert to using GIMP
GIMP can be installed from the Ubuntu Software Centre:
It can also be installed from the Fedora Software Centre: