So im new to anything other then 'looking' here.
How do i add a tag to some one else's post?
Especially say, 1>
ᅟ if said character displayed, is a commission Of my character(OC), but lacks a e621 tag for character Name?
Or 2>
ᅟ in another case has my name tag Wrong?

Click on the "Edit" button under the image. If your character's tag is incorrect, remove the wrong name and add the correct one. If you're creating a new tag, defer to forum #283267 for an in-depth tutorial about tag creation and categorization.

to edit the tags on any post click on the Edit button a bit below the image and a few boxes should show up including the tags box, you can add or remove tags here. character tags are normally in the format of <firstname>_<lastname> or <charactername>_(<owner>), tags are seperated by spaces. press Submit when you're satisfied with your changes.

after adding the tag you can find it on the tags list for the post and click on the ? next to it to bring you to the wiki page for your tag, on this page you can click the Edit Tag Type button to change its category to Character.

Thank you both for your advice. Helped bunches!