The Display Name within your Squarespace site is the name that appears next to content you've authored such as in journal comments and entries, discussion pages and guestbook modules. You can choose any name to appear as your Display Name and you can edit or change that name to your preference at any time.
After logging in to your site, your Display Name will be immediately visible in the top left side of your site interface. By default it will appear with the linked text Your Name Here until you've created a name of your own choosing.
To access your Display Name, click the Your Name Here link and select the Member Profile option from the drop down list displayed:
You'll be directed to the Member Account Management > Basic Information tab within your site where you can then update your Display Name.
Enter the name of your choice in the Display Name field and then click the Save Changes button to save your changes.