Just "float" it to the right side using a bit of CSS. For example, if your page looks something like this:
<img class="right-side large" src="https://i.imgur.com/XHupYIb.jpg"> Double-click this passage to edit it.
Lorem Ipsum is simply dummy text of the printing and typesetting industry.
<hr class="clear">
Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
... then this bit of story stylesheet will do what you want it to do:
img.right-side {
float: right;
}
img.small {
height: 3em;
}
img.medium {
height: 9em;
}
img.large {
height: 15em;
}
hr.clear {
clear: both;
border: 0;
}
The "class" part of the <img> tag tells it to "float" to the right of the text ("right-side") as well as determine it height in text lines ("small", "medium" and "large" correspond to 2, 6 and 10 lines respectively). The <hr class="clear"> inserts an invisible break in the text which does nothing if there is no image - or anything else - "floating" around the page, else forces the text following it to be below all the "floating" elements encountered so far.