Simply go to your blog's layout page. Click on 'edit' within the gadget that you want to center.
Add <center> to the beginning of the code and </center> to the end.
For example, I wanted to center the button for my blog. Uncentered, the code looks like this:
<a href=http://www.sneakymommablogdesign.blogspot.com
target="_blank"><img border="0" alt="Sneaky Momma Blog Design" src="http://i409.photobucket.com/albums/pp178/sneakymomma/smbdbutton-pb2.png"/></a>I added <center>to the beginning and </center> to the end, which resulted in this:<center><
a href="http://www.sneakymommablogdesign.blogspot.com"
target="_blank"><img border="0" alt="Sneaky Momma Blog Design"
src="http://i409.photobucket.com/albums/pp178/sneakymomma/
smbdbutton-pb2.png"/></a></center>
Some button codes come with built in centering tags. To make a centered button align with the non-centered items in your sidebar, remove <center> from the beginning of the code and </center> from the end. Be sure not to delete any other characters! :)
Happy Blogging!
Related Posts:
Center/Customize Your Sidebar Photos
Align Your Sidebar Gadgets
Get an HTML Code for a Button/Image
