I'll try to list your options:
The program that the vast majority of professional photographers, art designers, magazine photo editors, etc use is the 'full' version of Photoshop (which is currently Photoshop CC). However it's mega-expensive (at around £550 for a 12 month licence!) and has an extremely steep learning curves, so it's probably not what what you're seeking.
However there's a cut-down version of Photoshop, called Photoshop Elements, which is aimed at home users. (The current version is Photoshop Elements 12 but Photoshop Elements 11 is still available from some sources). It's not cheap (at around £75 for version 12, or around £60 for version 11, from Amazon) but it's widely praised and there are plenty of books available to teach you how to get the best from it, so (if you're serious enough about image-manipulation to want to pay that much money) it might be right for you:
http://www.adobe.com/uk/products/photoshop-elements.html
Corel Paintshop Pro X7 is a major rival to Photoshop Elements, with a roughly similar price tag. It's also well worth considering:
http://www.paintshoppro.com/en/products/paintshop-pro/ultimate/
GIMP is an open-source (i.e. totally free) image-manipulation program which seeks to do everything that the 'full' versions of Photoshop do. (It's used by impecunious professionals and students, together with many home users). It can certainly do everything you want but, just like the full versions of Photoshop, it's got a very steep learning curve. However, since it's a freebie, you might want to give it a try:
http://www.gimp.org/
(If you download it I STRONGLY recommend downloading the tutorial as well, otherwise you almost certainly won't have a clue about how it works!)
Google's Picasa software is popular and widely praised (and free!) but I've no experience of it myself, so I don't know how well it might meet your needs:
http://picasa.google.com/
However I think it's likely that Serif PhotoPlus might be best for your needs. There's a totally free Starter Edition available for download here:
http://www.serif.com/free-photo-editing-software/?MC=FSSPHOTOPLUS
The free version might be all that you need but the full (X7) version theoretically costs around £80. However I'd be prepared to be that, if you register the Starter Edition, you'll soon get an email offering you a
substantial discount on the X7 version. (I love Corel software. I used to be a member of their scheme that operated rather like a book club, whereby they offered me a different program each month. I ended up with loads of great software, all of which was excellent and I only left the scheme because I'd purchased just about everything that they had!).
There are lots of other commercial programs on offer, typically at around £10 to £30, in places like PC World. To the best of my knowledge (based upon reading a great many reviews in computer magazines and online) none of them can match the programs I've mentioned above.