It does matter yes. Where to put it is defined by how the content in the aside
tag relates to the main section
.
For example:
If the content in the aside
is related to the main article, it should be inside the main section
. However if the content inside the sidebar aside tag
is different to main
I would put it outside of the main section
http://html5doctor.com/aside-revisited/
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/aside