These are two of the most important and most woefully under-used tools on Neopoet.

The 'Edit' tab.
When you first post a poem you will see 3 tabs above the title 'View', 'Edit' and 'Unpublish'. You will receive feedback, hopefully offering suggestions for changes. If you choose to make any changes click on 'Edit' and it will take you back to the page where you first posted. There you can edit the poem. But this is most important! Remember to save those changes back to your computer, either replacing the original poem or saving it as "[title] rev 1" or 2 or 3 etc. The two reasons for this is that one, Neopoet is not archival, nor intended to be, it could crash or be closed. It is entirely your responsibility to backup your own work.
The second reason is that often you may receive a flood of suggestions and you need to keep your original poem intact in order to avoid losing your original vision in the face of other people's (well intentioned) suggestions. Called "throwing the baby out with the bathwater"

The 'Revisions' tab.
When a poet has revised their poem, either based on their own thoughts or other's suggestions you will see two tabs above the title 'View' and 'Revisions'. When you click on 'Revisions' you will see the changes made compared to the original. Often it is a long list. I normally click on the first and the last to see all the changes, but if you have made a particular suggestion you can click on the date after you made it and compare it to the most recent version. This is how those of us that care can see how a poem progresses, and whether or not the poet is listening or not.

I need to stress here that there is no obligation whatsoever to make changes based on people's suggestions, although I consider it polite to give a reply in comments about why I did or did not make a change.