I registered a domain at the beginning of this month, and install wordpress on it, and you know wordpress has a default post and comment, then I found my site was in Google, but in Google webmaster tool, my website keyword is something like "wordpress" even I continued to put four posts there with other keywords, but in webmaster tool, keyword just no change, do you know how long google will update it?
Means your site is not well indexed yet, bring more good content and strong backlinks for your site and soon things will show appropriately.
So it necessary to delete wordpress default post, page and comment at once after the installation of wordpress. You can disallow this pages on robots.txt. Continue posting on your blog and after some days google will pick up new keywords relevant to your blog and will show on the GWT.
I think your keyword is not so good that google does not pick up. Another is you should make quality back link as well as traffic.
You can use wordpress plugins like Meta SEO pack where you can control the keywords are in keyword meta tag. First check source of your page and look for keyword meta tag. You should see word wordpress in either keyword tag, title tag or meta description tag. If you see them, you need to remove them first and then can control tags for individual pages using Meta SEO pack.