Not sure how all this sorting works? Let's try an example:

1. Click Start, type Paint, and hit Enter.

2. Click File, Open, then navigate to a folder containing some images.

3. In the main pane, you should see columns with headers like Name, Date taken, Tags, and so on. No "Date modified"? Don't worry--by default it's not usually there (weird given how useful it is). To add it, right-click anywhere in that toolbar full o' headers, then click Date modified.

4. Now click the "Date modified" header to sort everything in the pane by the, um, date modified. Note that when that header has a teeny down-arrow along the top, everything will be sorted by newest to oldest. Click the header again to reverse the sort order (i.e. oldest to newest), as reflected by the teeny up-arrow.