@Louis,
[*pagetitle*] is a document specific template variable (TV) that comes with modx. It gets its value from the "Title" field of your document. When editing a document, you can see a "Title" field under the "General Tab" - it is the first field.
Say, you put
[*pagetitle*] in your template the way you’ve explained above. You then create a modx document in the editor, and you will give it a title, say
"Home". . For this particular document you have created (Home) modx will replace the placeholder
[*pagetitle*] with the title you gave your document, so
"Home" will be the title. If you have another page which you give a title, say
"Food", when viewing that particular page, the title of the page will be,
"Food".
Basically, whatever you put in the Title field for each document is what will appear in the
[*pagetitle*] . Meaning, you obviously have to edit your pages and give them unique page titles (assuming you want your pages to have unique page titles). If you leave the title blank, then you will get that - a page without a title. Hope I haven’t confused you further
Have you read Bob’s guides? I suggest you do this if you haven’t. Read them in concert with Susan’s guides (she gave you a link above). Bob’s are here:
http://bobsguides.com/MODx.html
cheers/k