How to change margin on my site

Hi

On all the posts on my website, there’s a big margin between the featured image and the text.
I want to know how to reduce this margin.
The following link is how it appears on my website: https://www.skintnation.com/travel/2012/05/fun-ways-spice-summer/

The original theme can be found here; the gap between where the featured image and the text should be as shown in this theme: https://themes.themesector.com/?theme=avenue

Thanks