Here are the directions for setting up your domain, if you purchased your domain through Square Space. 

Open Advanced DNS settings 
Scroll down to Custom Records
Select the Add Tab

Once the edit box opens add the data:

Host: this is where you put your subdomain word such as folios, newborns, families etc. 
Record: Choose A from the drop-down
Data: Add the StickyFolio's IP address:  

Click Add to save the record and complete the process. 

Once you have added the domain to Square Space, you can add the domain in the StickyFolios builder.