Testimonials and Link Manager

I installed the testimonials and link manager today and when i try to add testimonial it has an error

Warning: Cannot modify header information - headers already sent by (output started at /home/content/a/r/m/armieschoch/html/includes/languages/english/extra_definitions/define_testimonials_add.php:1) in /home/content/a/r/m/armieschoch/html/includes/functions/functions_general.php on line **44

**when i try to add link also the same error appears. what is wrong?

There are 100s of posts related to this php issue where if there are space(s) or blank line(s) before the starting php tag of <?php or after the last closing php tag ?> ... php will throw an error message like this as it hates those ...

To fix this problem, using a good TEXT editor, you can edit the file listed and remove the space(s) and/or blank line(s) at the beginning and end of the file ...