In order to export your Raiser’s Edge constituents to your data source, you’ll first need to create a constituent export in RE containing those records. Add any fields to the Output that you wish to export from RE.
The minimum fields required will vary depending on your data source so check those to ensure the export will run successfully.
If you are not familiar with using Export in Raiser’s Edge, you can find more in their knowledgebase here and in the Query and Export User Guide too.