Add partial view to Spree


I am new to Spree, so my question might look dump. How can I use
extension to add partial view to any existing view in Spree? How can I
determine exactly where my view will go? For my app I just want to add
a div block to /shared/_taxonomies.html.erb, is there anyway to do
this except overwriting this file with my extension? I have read
Extension tutorial several times, but I am not more clearer…