a little beginner question

Hello,

I changed my theme to “Almost Spring 1.0” using Word Press 1.5.1.3, only plugin used: Spam Karma 2 beta 4.

I have a very simple question. If I insert images into my posts like this: https://animeblog.sub-kultur.de/?p=67 , they have no margin to the text (its like this in every WP Theme). What do I need to change for images to have a distance to text like 5 pixels?

Thanks in advance