How to use Session and Hashtable in handler file

<![CDATA[<%@ WebHandler Language="C#" Class="Handler" %>]]>

using System.Web;
using System.Collections;
public class Handler : IHttpHandler, System.Web.SessionState.IRequiresSessionState
{
    public void ProcessRequest (HttpContext context) {

        if (context.Session["userpseb2014"] == null || context.Session["userpseb2014"].ToString() == "")
        {
            context.Response.Redirect("../Default.aspx");
        }
        
            Hashtable objHT = new Hashtable();
            objHT = (Hashtable)context.Session["userpseb2014"];
            string str = objHT["User"].ToString();
        
        
        context.Response.ContentType = "text/plain";
        
        HttpPostedFile uploadFiles = context.Request.Files["Filedata"];
        string pathToSave = HttpContext.Current.Server.MapPath("signsect/") + uploadFiles.FileName;
        uploadFiles.SaveAs(pathToSave);
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }
}