WebMerge can publish the data from any text file that contains data in a row-and-column format. The rows, or records, must be separated by return characters, and the columns, or fields, can be separated by any character, either quoted (",") or unquoted (,).
Nearly every database and spreadsheet program exports in a tab-delimited format, and some of those programs will include the names of the fields in the first line of the data. This is useful as it makes placing your tags much easier, since you can use actual field names in your templates. If your source file does not contain field names in the first line of its data, WebMerge will create field names for you based on the position of the field in the file (e.g., "Field_001", "Field_002", etc.).
If the program you're exporting from supports Merge format, that's the one you'll want to use. Merge includes field names and is ideally suited for this sort of task. FileMaker Pro, Microsoft Access, AppleWorks, and others support the Merge format (in Access this is listed in the Save As dialog as "Microsoft Word Merge").
You may need to consult the manual for your database or spreadsheet program for specifics, but most programs let you export by simply choosing File->Export, and then selecting the appropriate format from a list in the Save As dialog.
Some of the better database programs like FileMaker and Access provide rich scripting languages for you to automate the program's features. If you have a database file you'll be generating pages from often, you can write scripts to automate your export, and include steps for sorting and filtering to arrange your data in any specific way you need.
Once you've exported your source file, you're reading to bring it into WebMerge. See the section on the Sources Tab for details on having WebMerge work with your source file.