using Microsoft.SharePoint.WebControls;

public SPFieldUserValueCollection GetSelectedUsers(PeopleEditor editor)

{

       string selectedUsers = editor.CommaSeparatedAccounts;

       // commaseparatedaccounts returns entries that are comma separated. we want to split those up

       char[] splitter = { ',' };

       string[] splitPPData = selectedUsers.Split(splitter);

       // this collection will store the user values from the people editor which we'll eventually use

       // to populate the field in the list

       SPFieldUserValueCollection values = new SPFieldUserValueCollection();

       // for each item in our array, create a new sp user object given the loginname and add to our collection

       for (int i = 0; i < splitPPData.Length; i++)

            {

                string loginName = splitPPData[i];

                if (!string.IsNullOrEmpty(loginName))

                {

                    SPUser user = SPContext.Current.Web.SiteUsers[loginName];

                    SPFieldUserValue fuv = new SPFieldUserValue(SPContext.Current.Web, user.ID, user.LoginName);

                    values.Add(fuv);

                }

            }

            return values;

        }

}

SPList list = SPContext.Current.Web.Lists[APPLIB];

SPListItem item = list.Items.Add();

item["ProgramAdmin"] = GetSelectedUsers(txtScope);

item.Update();