First you need to create a presence here on HubPages and you can do it in the following ways:
1. Post high quality content hubs
2. Follow all guidelines (check out the learning center)
3. Be an active member by commenting on other hubs and helping others
4. Apply for the earnings program (I recommend doing this after you have published at least 15-20 Featured hubs)
However, being active on HubPages increases your credibility and will inadvertently increase your earnings as well. Happy writing!