For a few pages, particularly if you know which ones, use the "Old Revisions" tab which shows you the detail. For an automated search you will need to look at corresponding pages in
meta. For example:
$ grep -o -r jmr meta | grep '.changes:' | sort -u
will return a list of all meta change files where the user "jmr" is listed. You can then look at the individual files that might be of interest. The format is:
1475012116 ::1 C add_dvd jmr created
1495902007 ::1 E add_dvd jmr msn
1495923828 ::1 E add_dvd jmr Instructions
which shows the timestamp (column 1), DW's user ID (::1), Create or Edit, page name, user name and edit summary.