Custom Footer

First enable the custom footer for your site: Gear icon (upper right) > Edit site layout > and enable custom footer. 

It allows you to format your content using HTML and some basic inline CSS. 

Note: you can not insert a gadget in the custom footer. 

The method I used is to create a table, copy the code for it and paste it into the html of the custom footer.

<table border="1" bordercolor="#888" cellspacing="0" style="border-collapse: collapse; border-color: rgb(136, 136,136); border-width: 1px;">
<td style="width: 25pc;">&nbsp;Column one</td>
<td style="width: 25pc;">&nbsp;</td>
<td style="width: 25pc;">&nbsp;</td>
<td style="width: 25pc;">&nbsp;</td>

See this discussion in the help forum.

Also see the footer here and on this site.