Hi Henning,
There is no need to code anything in the page.xml. Please follow the given steps :
1. To Create static block :-
Magento Admin -> CMS -> static block -> Add new block -> Fill all the necessary boxes marked with red star.
2. To place the static block created above :-
a) Magento Admin -> CMS -> Widgets -> Add new Widget instance .
b) In the Settings section
Type -> CMS static Block
Design/theme -> name of working theme and Continue
Fill all the necessary boxes marked with red star.
3. In Layout update section , click the Add Layout Update button. Then, do the following:
a) In the Display On field, select the page where you want to block to appear.
b) Set Block Reference to the position on the page where you want the block to appear.
4. In the panel on the left, select Frontend App Options. Then, do the following:
a) Click the Select Block button.
b) In the list, click to select the block you want to place.
and in last Save.