To connect to Amazon Glacier, you need a credentials key pair (Access Key and Secret Key). The first time you launch Freeze, you will be asked for your key pair to create a new account. You can either create a root key pair or an IAM user with restricted permissions (recommended).
To create a key pair restricted to Amazon Glacier:
AmazonGlacierFullAccess
Now that you have your credentials key pair, launch Freeze and enter Access Key and Secret Key within the "Add new account" window. You may also choose an account name to help you differentiate it from other accounts.
If you are using a key pair restricted to certain regions or if you simply want to prevent yourself from uploading data to the wrong regions, you can disable regions for a specific account. To do so, select "Regions" -> "Select regions..." within the account window to open the regions selector. Deactivate any regions you don't plan to use.
Choose regions geographically near you for the fastest possible transfer rates. Also keep in mind that regions have different prices. For example, Frankfurt is more expensive than Ireland.
Not all regions are enabled by default in your AWS account. You might need to visit the AWS Regions page and enable regions before they can be accessed.