Here is an example with a Belgian OSM server. You can obviously choose another one.
# Map Tile Layer, using OpenStreetMap tiles fetched from a Belgian server
OsmTiles.class=com.bbn.openmap.layer.imageTile.MapTileLayer
OsmTiles.prettyName=OpenStreetMap Tiles
OsmTiles.tileFactory=com.bbn.openmap.dataAccess.mapTile.StandardMapTileFactory
OsmTiles.mapTileTransform=com.bbn.openmap.dataAccess.mapTile.OSMMapTileCoordinateTransform
OsmTiles.emptyTileHandler=com.bbn.openmap.dataAccess.mapTile.ShpFileEmptyTileHandler
# Define ocean/background colors for tiles
OsmTiles.background.fillColor=FFFFFF
OsmTiles.background.lineColor=FFFFFF
# Define land color for tiles (empty tiles on land, too)
OsmTiles.land.fillColor=DECD8B
OsmTiles.land.lineColor=DECD8B
# Define zoom level to limit handler response - zoom in past this provides empty coverage (clear)
OsmTiles.noCoverageZoom=13