They look fine, but there are a few points that might help you:
1. That number of hubs would be okay for about a month. You need to write more to generate more interest and earn more. Do you have more on the Excel or other subjects?
2. You should make the titles a lot more user friendly. No one is going to search for "Excel-User Tutorial: How to Use Excel" but there are a lot of searchers for "How to use excel". Marisa Wright, Simone, and others have written on this subject on the forums, so you might want to take a look.
Good luck. It is slow starting out so you just need to stay focused, positive, and as Clark mentions, write WAAAAAY more.