"The basic difference between being assertive and being aggressive is how our words and behavior affect the rights and well being of others." - Sharon Anthony Bower
Assertiveness is a set of behaviors that allows you to express your feelings, opinions, beliefs, and needs directly, openly and honestly in a positive way.
Assertiveness differs from aggression in fundamental ways. Aggressive people force others to meet their needs by using unpleasant means such as shouting, physical roughness, manipulation, or threats. In contrast, assertiveness is being able to express feelings, ask for something, or set limits without demanding results or intimidating people.
The links below may help you become more assertive.