how to call a javascript or jquery function in code behind

protected void lbt_Click(object sender, EventArgs e)
{
System.Text.StringBuilder sb = new StringBuilder();
sb.Append("$(document).ready(function(){");
sb.Append("$.showprogress()");
sb.Append("});");
ScriptManager.RegisterStartupScript(up, up.GetType(), "Script", sb.ToString(), true);

}