usually the changes are in a series of commits one after the other. start from first read all the comments and try to understand if they suggest some small changes or something which spans multiple commits and is related.
let's say there's no such big change suggested, which is ususally the case, then you start from the very first commit in the series and implement the suggested changes. don't mark the comment as resolved yet as these suggestions don't just apply to one commit, make sure you look through other commits to see if this suggestion applies there and if it does, make the fixes in those commits and then resolve this comment. do it for reach comment.
when you are fixing something, make sure that you test the fix on top of the commit series and once it works there, you can just stash the changes and apply and ammend them to a particular commit in interactive rebase. the idea is to not checkout to a particular commit and then implement the fix as that fix might not play well with the following commits and then it would be just more work to test it twice (and potentially fix it twice).