PopulateValues

[SitecoreClass(TemplateId = "My-Guid-Here")]
    public class DictionaryDomain : GlassBase {}

[SitecoreClass(TemplateId = "My-Guid-Here")]
public class DictionaryEntry : GlassBase
{
    [SitecoreField]
    public virtual string Key { get; set; }
    [SitecoreField]
    public virtual string Phrase { get; set; }
}

[WebMethod]
public string MakeStates()
{
    ISitecoreContext context = new SitecoreContext();
    string[] states = System.IO.File.ReadAllLines(Server.MapPath("StateList.txt"));
    DictionaryDomain dictionary = context.GetItem<DictionaryDomain>(Guid.Parse(Core.Constants.Dictionaries.States.DomainId));
    
    PopulateValues(states, dictionary);
    return "Successful!";
}

/// <summary>
/// Adds items to a dictionary given the dictionary domain 
/// and the existing items
/// </summary>
/// <param name="items"></param>
/// <param name="existingItems"></param>
/// <param name="dictionary"></param>
private static void PopulateValues(IEnumerable<string> items, DictionaryDomain dictionary)
{
    var existingItems = 
        dictionary.GetChildren<DictionaryEntry>(Core.Constants.Dictionaries.DictionaryTemplateName).ToArray(); 
    foreach (string item in items)
    {
        //Check to see if the item already exists before adding it
        if (existing.Any(a => a.Key != null && a.Key.ToUpper() == item.ToUpper()) || string.IsNullOrEmpty(item)) continue;
        ISitecoreService service = new SitecoreService("master");
        using (new SecurityDisabler())
        {
            DictionaryEntry entry = 
                service.Create(dictionary,
                new DictionaryEntry
                    {
                        Key = item.ToUpper(),
                        Phrase = item.ToUpper(),
                        Name = item.ToUpper()
                    });
            service.Save(entry);
        }
    }
}