There are 3 modes of editing a page:
1. Whole page edit
This mode locks the whole page for you during the editing time. If the page is not long this will not be a problem for you.
At the bottom of each page you will find some buttons. The most left on of these is exact the button which starts the "Edit the page" Frame for the whole page:
A click on this button opens a new page consisting of the "old" content of the page and a new section "Edit the page" (or use the typical "CTRL + e" for the same effect):
This frame contains an editor window where You can enter Your text. Above You will see some helping buttons (sometimes with wizards) . Hover your mouse cursor of the buttons and a little Tool-tip will appear.
Under the Editor-window there are 2 helpful links inserted , which opens in an extra window:
For the history screen ( better called "revisions") it seems to be a good idea to fill in a short description of your changes:
On the right side of this short description window is the Lock information shown:
If the Editor-Window is to big for your screen - on the right bottom of this Editor-window You can zoom in/out - means make this window smaller or bigger:
And at the bottom of the "Edit the page" frame there are the buttons to save Your work ( or discard it):
- cancel is clear - you will loose all Your work without any security question. The same happens if You press too much the "Escape" button on Your keyboard( in panic or so).
- view diff - this is helpful to control Your last changes in a little extra - frame before you save the changes (with an included example); to close this frame "Diff changes" click on the little button "close diff view":
:
- preview - a good idea to have a look before you press any save button.
- save & continue - this saves your work and you can continue without going to the edit buttons again.
- save - this saves your work and the page is re-sent to your browser with the new content(or use the typical "CTRL + s" for the same effect).
2. Section edit
This mode only locks one section - defined by the header selected - instead of the whole page for You during the editing time.
This is useful if the page is long and You do not want to stop other Authors from writing.
To open this mode You have to switch the "+options" button (bottom -right side)
to "-options": 
You have got the extra buttons line with the left most button "edit_sections" : 
If You click on this button every Section in your page (this is defined by any header-line big enough for this - normal down until level 2) will get in the Header-line (the line with the + or ++) an edit button on the right side:
You can use this button to edit the selected section alone without disturbing or changing the rest of the page. Note this is a flip-flop button, setting the section edit allowed or not. And a the moment with the save or discard of Your change the extra button line (by +options) are gone. Could be in next releases this will change.
The only difference to the editor-window from the Whole page edit mode:
the button save & continue is not present…
3. Append
In this mode You can only append a text to the whole page content:
You will find the button to do this in the "+options" :
there is the second button in the extra buttons line:
The Editor-Window "Edit the page" opens as usual - but You have no "view diff" and no "save & continue" button.
Some notes
In case You use of one of the save-buttons: please wait for the acknowledgment ( "page saved") - otherwise You will loose the changes!
if the page "hangs" with a running cursor - try the save button again. The experience says it helps sometimes.
Since the changes of 2007-07-26 the "CTRL+e" and "CTRL+s" does the same as the "edit" and "save" buttons.
