The following code obtains the layer symbol table from the database, creates a new layer table record, and names it (ASDK_MYLAYER). The layer table record is then added to the layer table.
void
createNewLayer()
{
AcDbLayerTable *pLayerTable;
acdbHostApplicationServices()->workingDatabase()
->getSymbolTable(pLayerTable, AcDb::kForWrite);
AcDbLayerTableRecord *pLayerTableRecord =
new AcDbLayerTableRecord;
pLayerTableRecord->setName("ASDK_MYLAYER");
// Defaults are used for other properties of
// the layer if they are not otherwise specified.
//
pLayerTable->add(pLayerTableRecord);
pLayerTable->close();
pLayerTableRecord->close();
}