SiteUserInfoList in SharePoint 2010

            SPSite site = SPContext.Current.Site;

            SPWeb objWeb = site.RootWeb;

            objWeb.AllowUnsafeUpdates = true;

            SPList list = objWeb.SiteUserInfoList;

            SPField field;

            if (!list.Fields.ContainsField("FieldName"))

            {

                field = list.Fields.CreateNewField(SPFieldType.Text.ToString(), "FieldName");

                list.Fields.Add(field);

                list.Update();

            }

            else

            {

                //list.Fields.Delete("FieldName");

                //list.Update();

            }

            SPSecurity.RunWithElevatedPrivileges(delegate()

            {

                SPWeb web = SPContext.Current.Site.RootWeb;

                //Save values to user profile list

                SPUser user = web.CurrentUser;

                SPListItem userItem = web.SiteUserInfoList.GetItemById(user.ID);

                userItem["FieldName"] = 1025;

                userItem.Update();

            });

            //Read values from user profile list

            SPUser user1 = SPContext.Current.Web.CurrentUser;

            SPListItem userItem1 = SPContext.Current.Site.RootWeb.SiteUserInfoList.GetItemById(user1.ID);

            string languageID = userItem1["FieldName"].ToString();