First, be aware that the text+image iframe links generated by the standard Amazon "Build Links wizard" are a little smaller than those created by the Amazon Blogger tool, which adds padding to the iframe.
Standard text+image iframes
For the Amazon text+image iframes shown below, I used a CSS class, iframe.inrow, to display the iframes "inline". By default, iframes are block elements. Like paragraphs and divs, there is a automatic line-break between them. When displayed inline, they are more like words in a paragraph, and will wrap if there are too many to fit on one line.
To display iframes side-by-side, add this class to your stylesheet:
iframe.inrow {display:inline;}
To add more space between iframes add a right margin to the style:
iframe.inrow (display:inline; margin-right:10px;}
To add space between the iframes, add padding:
iframe.inrow (display:inline; margin-right:10px; padding-top:5px;}
To apply the class add it to the <iframe> tag:
<iframe class="inrow" src="... "></iframe>
In the next example row, iframes are floated left. You could add this style to your stylesheet:
iframe.fleft {float:left;}
To add more space between rows of iframes, add padding to the style:
iframe.fleft (float:left; margin-right:10px; padding-top:5px;}
If you prefer, you can simply paste the style into each iframe's existing style attribute:
<iframe ... style="display:inline; margin-right:10px; padding-top:5px; width:120px; height:240px;" ...></iframe>
Blogger Tool generated text+image iframes
The text+image iframes generated by the Blogger tool include a style of padding-right:10px, and an HTML attribute of align="left" so a right margin is not necessary to separate the iframes. They will align in rows by themselves. However, if you want to make the code standards-compliant, you could use the CSS style "display:inline" or "float:left" and delete the bogus CSS "align:left" style and the HTML attribute: align="left". The obsolete iframe attributes marginwidth and marginheight can also be safely removed. When displayed inline, the iframes will wrap, just like words in a paragraph, if there are too many to fit on one line.
The most common problem with iframes created by the Blogger Tool is simply that the white background may not match your background color. To fix that problem, edit each iframe tag in the HTML editor. Find "&bg1=FFFFFF" and change FFFFFF, which is the hex color code for white, to the code for your background color.
The following rows of iframes were added using the Amazon Blogger tool. Notice that their height is 245px with top padding of 5px, instead of the usual 240px.
The first group has a class of inrow2. In the examples below, the iframe width has been changed from 131px to 120px, and padding-right is 10px:
iframe.inrow2 {display:inline;}
To apply the class add it to the <iframe> tag:
<iframe class="inrow2" src="... "></iframe>
You could also use the CSS style "float:left" to achieve the same effect. The iframes below are floated left.
iframe.fleft {float:left;}
If the iframes are not enclosed in a block element, such as a paragraph or div, you will need to clear the float at the end of the iframes.
Again, you can add either style directly to the <iframe> tag. The invalid style "align:left;" is ignored, but should be removed if you want your code to validate. The HTML attribute align="left" should also be omitted. The style becomes:
style="display:inline; padding-top:5px; width:120px; height:245px; padding-right:10px;"
OR
style="float:left; padding-top:5px; width:120px; height:245px; padding-right:10px;"
I hope this explanation clears up some of the confusion surrounding text+image iframes.