Why can I not add comments on a post? It says I have to have 50 reputation points. I looked under reputation and it says I do not need any points to comment, please help.
You don't have enough reputation to comment on other people's questions/answers.
Per the FAQ;
Privilege Type: Communication Privilege
Awarded At: 50 Reputation
Please note that you can always comment on your own posts, and any part of your questions. However, commenting on other people's posts is a privilege.
If you want to post general comments, you'll need at least 50 reputation points. This is to stop "drive-by" commenters from posting worthless comments on questions and answers that they've found through google.
For reference, the quickest way to get 50 points is by posting a high quality answer or asking a question about a popular recent film.