Before moving on to photo-editing software, I'll offer you a suggestion for printing photos out to a desired size, which has nothing to do with such software. That's simply to use word-processing software (such as Microsoft Word, OpenOffice Writer or similar) or, possibly even simpler, a desktop publishing program (such as Microsoft Publisher or Scribus). Simply open a blank document, import your photo into it and then adjust the image size (by dragging a corner of it) until it meets your requirements. (Most of the types of programs I've suggested give you fine control over the image size via right-clicking on it and then adjusting its properties). My suggestion isn't just pure 'theory'; it's the way that I print out images to specific sizes myself!
Returning to the core of your question though, for such simple photo-editing tasks, I'll suggest a program which is best known as an image
viewer (rather than as an image 'editor') but which actually has all the options you require hidden under the bonnet:
It's the might Irfanview (which is always one of the first programs I install when setting up a new computer, whether for myself or for someone else). Although I've got both Photoshop and Gimp on my computer, I only use them for complex tasks; it's always Irfanview that I go to for the 'day to day' stuff:
https://www.irfanview.com/
To crop an image in Irfanview, just use your mouse to draw a rectangle around the desired area and go to Edit > Crop Selection (or, simpler, hit Ctrl and Y together).
To change things like the brightness, contrast, saturation and colour balance, go to Image > Color Corrections (or just press Shift and G together; the shortcuts come naturally to you after a while!).
There are LOADS more things that Irfanview can do (and all of them incredibly easily too) but, if you decide to give it a go, it would be best for you to simply play with it for a while to see if you like it.