In order to get bigger pictures on your blog,Blogger Help forum

In order to get bigger pictures on your blog
Open a googlesite (using your e-mail and password - or using another e-mail
and password ) and save (store) in it your photo or pic of over 1600px(height or
length) , then recall it (upload it) using the photo's actual " "web address" "
from the googlesite you have created and it will appear to your blogspot (when
resizing) to its total size of over 1600px(height or length).
Please read this carefully and pationtly and you will have
your results. It took me three years to find out this .
http://www.google.com/support/forum/p/blogger/thread?tid=1d986bccc636ff33&hl=en
Blogger Help forum:how do i enlarge pictures on my blog?