Twenty thirteen – space between paragraph

Hi,

I’m using Twenty thirteen, I’ve created a child theme, I need to adjust the space between paragraph, I’m a newbie with CSS, any help is welcome!

I leave this image to clarify my question (red arrows): http://infoviajera.com/wp-content/uploads/2015/01/WordPress_Paragraph_Adjust.png

Kind regars,

Jorge

P.S.: Please forgive my English 🙂