How to configure a robots.txt file for WordPress?

Hi.
I need a robots.txt file for WordPress, a good configuration because my content of the posts, are not directly displayed on Google under the title of the post.

For example:

Title of the post on Google: Free WordPress Tutorials 2013.

The content of the post: Here you can the best WordPress Tutorials for beginners, bla bla bla.
This is a normal index.

So, normally, in the Google Engine, under the post title, it has to appear directly the content post.

My problem is that in my WordPress blog, the content post doesn’t not appear on Google directly.

It appears like “THE WEBSITE DESCRIPTION” or “THE KEYWORDS” or something else.

Please help me with a GOOD ROBOTS.TXT file.

Thank you in advance.