Please include always the version of jqGrid, which you use (can use), and the fork (free jqGrid commercial Guriddo jqGrid JS or an old jqGrid in version <=4.7).
It I correctly understand your question you can add onSelectRow
callback to the main grid (the only grid on your first page). Inside of onSelectRow
callback you can assign location
to new URL to redirect to another page. You can append to the URL some additional parameter, which will be used by the second (detailed) page to load/display the details of the required item. In the simplest case it could be:
onSelectRow: function (rowid) {
location = "secondPage.html?item=" + encodeURIComponent(rowid);
}