This example shows how to get the value of the current user's session, and then create a new “Contact” session for the user to gather information about the user's scope, budget, and business problem.

function displayContact(request, response) {
	var ctx = nlapiGetContext();
	var step = ctx.getSessionObject('stage');
	if (step == null || step == "") {
		step = "create";
		ctx.setSessionObject('stage', 'Contact');
	}
	if (step == "create"); {
		ctx.setSessionObject('scope', request.getParameter('scope'));
		ctx.setSessionObject('approved', request.getParameter('budget'));
		ctx.setSessionObject('problem', request.getParameter('businessproblem'));
	}
}

That's from the NS help docs on the nlobjContext object.