public class WorkSetHelper

 {

        public void AddElementsToWorkSet(Document doc, List<Element> elements)

        {

            if (doc.IsWorkshared == true)

            {

                var workset = GetWorkset(doc);

                if (workset != null)

                {

                    var worksetID = workset.Id.IntegerValue;

                    using (Transaction tran = new Transaction(doc, "[ToolSet] Add Elemens To WorkSet"))

                    {

                        tran.Start();

                        foreach (var ele in elements)

                        {

                            Parameter wsparam = ele.get_Parameter(BuiltInParameter.ELEM_PARTITION_PARAM);

                            if (wsparam != null)

                            {

                                wsparam.Set(worksetID);

                            }

                        }

                        tran.Commit();

                    }

                }

            }

        }

        public Workset GetWorkset(Document doc)

        {

            Workset newWorkset = null;

            // Worksets can only be created in a document with worksharing enabled

            if (doc.IsWorkshared)

            {

                string worksetName = "WorkSetName";

                // Workset name must not be in use by another workset

                if (WorksetTable.IsWorksetNameUnique(doc, worksetName))

                {

                    using (Transaction tran = new Transaction(doc, "[ToolSet] Create Work Set For ToolSet"))

                    {

                        tran.Start();

                        newWorkset = Workset.Create(doc, worksetName);

                        tran.Commit();

                    }

                }

                else

                {

                    IList<Workset> worksetList = new FilteredWorksetCollector(doc).OfKind(WorksetKind.UserWorkset).ToWorksets();

                    foreach (Workset workset in worksetList)

                    {

                        if (workset.Name.Contains(worksetName))

                        {

                            return workset;

                        }

                    }

                }

            }

            return newWorkset;

        }

 }