You simply place a dash before your negative keyword to use this option (ie ‘-internet marketing course’). Now if a user searches for ‘marketing course’ on Google your ad will be shown, it will not however be shown when the term …

Read more here:
Google Adwords Guide

Tagged as: a-dash-before, a-user-searches, dash-before, negative, option, simply-place, term, the-term, user-searches, will-not, your-negative