The article I linked to is designed for very beginners. It is part of our WordPress Lessons for novices. I know it might feel intimidating at first, but if you go through each paragraph slowly, it does make sense.
When you add an image through WordPress, you have an option to set the image to the right, left, or center. When you do, a bit of code is added to the image's code to tell it where to sit within the paragraph. If that is not correct, or the WordPress Theme is too old and doesn't have the current alignment styles, it won't "wrap" right.
I checked the Theme and the padding and margins for the CSS class for "alignleft" is not sufficient to push the text over off the image. Contact the Theme author for an updated fix or consider using another WordPress Theme is fixing this may be beyond your abilities and is really not your responsibility.
Sorry the Theme is doing this.