To use eselect news;
eselect news list
eselect news read all

If you only want to read new items;
eselect news read item_number

This resets the read/unread markers for the main Portage tree:
rm /var/lib/gentoo/news/news-gentoo.*
find /usr/portage/metadata/news -mindepth 1 -type d -printf "%P\n" \
> /var/lib/gentoo/news/news-gentoo.unread

eselect news list will then list all news items. Note that news items are tracked per overlay, by repository name (gentoo is the main tree). Files named news-foo.* track news for overlay foo.