That arranges them vertically. Is there any way to have them in a horizontal row?

Here is the code I'm using. The break tag may be somewhere that I can't figure out.

<center><a class='serendipity_image_link' href='/ed/blogs/Drury_Jon/uploads/shells1.JPG'><!-- s9ymdb:6 --><img width="100" height="133" style="float: left; border: 0px; padding-left: 5px; padding-right: 5px;" src ...

I am miserable at html, and the photos I have currently posted in an entry (thumbnails with links to larger images), instead of arranging in a straight row, are showing up diagonal to one another (see the entry to see what I'm talking about).

Can anyone tell me how to fix this?

Thanks in advance ...