The absolute positioning that sashi sugests should work, however it has some drawbacks, when you use absolute positioning the item postioned comes out of normal document flow. Normal document flow is how the browser positions everything automatically, when the image is no longer in normal document flow the browser will just ignore it as far as deciding where to position everything else.
The effect of this is if the image is embedded in some text, for instance, then when you absolutely position the image the text will just flow behind (or infront) of it, it will not go round it.
Another method of positioning an image (or anything else for that matter) is to float it, you can float it on the left or right like so
[html]<img style="float: left;" src="circle.gif">[/html]
A floated image appears on the left (or right) hand edge but it remains in normal documnet flow so the text it is in would flow round the image.
It is hard to give more advice with more information about what you are trying to achieve.
Finally using the inline style attribute as both sashi and I have done is bad form, you can have your styles in a section at the top of the file or in a separate file (recomended). This however is a CSS question, I would recomend a basic tutorial on CSS which will tell you about this.
http://www.w3schools.com/css/css_howto.asp