The following two links might be useful.
The file/directory structure is fairly simple. You have your home directory and within this will be separate web accessable sub-directory for each of your domains (or sub-domains), by default these sub-directories are named the same as your domain (eg: mydomain.com).
Normally, you would use an FTP client to upload your files to DreamHost, not an SSH client. DreamHost provides a web-based FTP client for those that do not have access to a 'real' FTP client.
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