With the bookmarklet, the tag window is obvious, just type the tag in the small window at the bottom of the pop-up window ( you also have a box that is selected by default to 'share' the clipping that you've highlighted, if you deselect this option the clipping will still be published but only on the 'tagged' feed ). Click Post  and the item will be published. But how do you access the feed? I'll get to that.

In the other three options ( Shared items, notes and People you follow ) the tag window is hidden, and can be viewed after you left click in the module where you type your note. As in the bookmarklet, you will be given an option to share, and 'Show Options'. Click on the latter. A small window will appear where you can type your tag ( I am creative with my tags, and try to be intuitive as the tags mirror my own thoughts and help me organize a very long list ).

Go ahead and tag a item ( from a news feed, or one your contacts have shared ). It really doesn't matter what article, or what tag you use as both can easily be deleted later.

Here is a rss feed from the tag 'tech tutor'. Notice; at the top of the page you will see the title of the feed,

All of my feeds have the suffix, 'VIA WALLACE REID'. Yours will have your screen-name as a suffix. Here's how to find, and publish your feed;

1. Look to the bottom of your side-bar in GR for 'manage subscriptions'.
2. Click there, and a new page will open in GR ( Settings, but not settings for People you share with ).
3. Click on the third tab from the left at the top of the page; 'Folders and Tags'.
4. Your page should display a list starting with starred and shared items. Tagged feeds are listed alphabetically below those two.
5. Find the tag you made, and click on the box directly to the left.
6. Now look at the header of the page for a little window displaying 'change sharing'. Click on the arrow ...
7. A drop-down window will allow you to choose between public and private.
8. Click on public, and then un-tick the box next to your tag. Three tabs ( hyperlinks ) should appear directly to the right of your tag; View Public Page, Email a Link and Add a clip to your sight.
9. Click on View Public Page. This should display the clipping on a plain Google page. The you can copy the url to share it with friends.

As I read my news feeds, I tag items of interest. GR manages all those tagged feeds on the 'manage subscription' page. If you go back to your main GR page and look at the header you will find a search box with many options. If you know that you've read and tagged an item but can't remember exactly where you published it, click on notes and type in some relevant words. GR will search your feeds. I use GR as my own personal data base.

Technically, all feeds that you make public are 'shared'. But only those that you mark as 'shared' ( it's default in all four of the pages ) will be available for comment. However, all items that are commented on are available to be tagged.

If you chose to publish this email as a shared note, I would be able to comment on that note and tag it as 'Google Reader Development'