People contribute in many ways :
1. Skilled programmers create resources online for Bitcoin to grow.
2. Semi skilled people create positive content to increase awareness .. {Posting on forums / Demonstration videos on Youtube etc.}
3. People with NO skills, increase awareness with "word-of-mouth" to friends and family and asking for merchants to accept Bitcoin.
Every little positive thing you do, makes a difference. Even if you only post something small on a forum, where someone needed help with Bitcoin information.