IIS - Directory Access Denied

I'm using windows server 2008 and IIS 6.1, I have a service that needs to access files in a particular directory, but I do not have access.

What do I need to configure to gain access?

AfteraddingAdministratorastheuser,theapplicationsaysthatthedirectorydoesnotexist.

List<FileInfo>files=newList<FileInfo>();if(Directory.Exists(@"C:\Users\Administrator\Documents\MovieCollector\PacotesSerializados"))
    {
        foreach (string file in Directory.GetFiles(dataFilePath))
        {
            FileInfo fileInfo = new FileInfo(file);
            files.Add(fileInfo);
        }
    }
    else
    {
        throw new Exception(dataFilePath+ " não lexiste");
    }

    files.Sort((x, y) => y.CreationTime.CompareTo(x.CreationTime));

    if (files.Count == 0)
    {
        throw new Exception("Lista vazia");
    }