Passing Session value to Generic Handler using C# and VB.Net in ASP.Net

Hello, based on this article https://www.aspsnippets.com/Articles/Implement-jQuery-AutoComplete-TextBox-using-Generic-Handler-in-ASPNet-using-C-and-VBNet.aspx, can you help me and explain to me how can i pass an additional parameters to the .ashx page? I need to pass to this page a value read from a textbox inside my vb.net page... Thank you in advance