You can follow these instructions to prevent other people from editing your pages.
First, log in using the "Log In" button on the top right, then find the appropriate space:
This will take you to the home page of the space you have selected.
Next, click the Add > Page button:
You are now editing a new page. You can add content, then click the "Unrestricted" button to add restrictions to the page:
This will bring up the page restrictions dialog.
Select "Restrict editing of this page", then you can start typing in the students name or usercode in the box. Start with your own, then add any others in your group. As you type, the autocomplete bubble will appear below - click the user you want then click "Restrict".
Now you can Save your permissions, and then Save the page edit.
If you need to check or change your permissions later, you can click "Tools" then "Restrictions" while viewing your page: