I have a site made in Blogger that offers free Wordpress themes download.

Now I'd like to make money on it using Adsense but my problem is it does not have enough traffic.

Where could I get traffic to this kind of niche?

Hy.

For my opinion you should focus on ranking your website, #1 will sure drive you traffic, and the income....

From my little experience and here I'm talking most from what I have read around here and over the web the best way to do it is to search for a low competition keyword with a lot of traffic and reach #1, this and keep your blog up to date and with new content sure will make you see the income.

Thank you.

Maybe leaving comments on wordpress pages that could use better themes
You can also contact the owners of certain Wordpress sites and let them know about it