I checked http://ingridribelli.wordpress.com/ and I see that you are currently using the Under the Influence theme there.
To add more space after each post (before the next headline), add this to your Appearance → Custom Design → CSS page:
.post {
margin-bottom:50px;
}
I also noticed that the background image you picked makes the text a bit hard to read at http://ingridribelli.wordpress.com/ One way to get around that might be to add a background color for the main content areas of the site like posts and widgets. Here is an example of CSS you might use to do that if you're interested:
.post, #sidebar, .widget {
background-color: white;
}
#sidebar {
margin-top: 10px;
padding-top: 0;
}