If you were trying to say "me, myself, and I" then it means that nobody helped you accomplish something.
Yourself is made up of two words, your self. It basically means you. Its not a hard word to understand.
Details about you
it means to say what you want to say or Stand up for yourself like be brave to talk to a bully
It means to be conceited, or to have a high opinion of yourself - 'He's got tickets on himself if he thinks I'll go out with him', etc. Its basically telling you to get over yourself.