I have a special paragraph I want to put a border around. How do I do that?
Format → Paragraph, then go to Borders tab.
Alternatively, if your paragraphs have received specific styles, modify the style pertaining to paragraphs-to-be-bordered using the same tab as above and all paragraphs sharing this style will be enclosed in the chosen border.
If this answer helped you, please accept it by clicking the check mark 
to the left and, karma permitting, upvote it. If this resolves your problem, close the question, that will help other people with the same question.