Hi Gien,
you have to log-in and then click “pages” on the left. There is your page to edit.
Here is a litte tutorial on how to use the wordpress editor.
You’ll see that the editor gives you some more options then described in the tutorial. This is because we have installed some extra things. The plugin “easy bootstrap shortcodes”. Here is a tutorial about the other options.
More info about the whole platform and OSCEdays infrastructure you can find at point 4 of the longer comment by Sam (@ cameralibre) here.