Hi,
you can read querystring params using the following macro:
{% PARAMETER %}
see Query string macros:
https://docs.kentico.com/display/K82/Macro+syntax
To load the values of query string parameters from the URL, use macros in format: {% parameter %}
Query string macros support all K# syntax. The names of all available query string parameters automatically work as variables that store the value of the corresponding parameter.
For example, on pages with URLs like /Home.aspx?nodeid=10, {% nodeid %} resolves into 10.
Alternatively, you can get the values of query string parameters inside standard macros: {% QueryString.parameter |(identity)GlobalAdministrator%}
Greets,
David