//Set up SPAPI (in my case I have installed SPAPI in Layouts directory)
<script src="/_layouts/SPAPI/SPAPI_Core.js" type="text/javascript"></script>
<script src="/_layouts/SPAPI/SPAPI_Lists.js" type="text/javascript"></script>
<script type="text/javascript">
 
//You may need do modify this function depending where your site collection is located
function GetRootUrl() {
    var pathparts = document.location.pathname.split('/');
    var url = '/';
    return url;
}
 
var lists = new SPAPI_Lists(GetRootUrl())
 
//quering last created item by current user
//i'm using _spUserId to get current user
var items = lists.getListItems(
        'Orders',   // listName
        '',         // viewName
        '<Query><OrderBy><FieldRef Name="Modified" Ascending="FALSE"></FieldRef></OrderBy><Where><Eq><FieldRef Name="Author" LookupId="TRUE"/><Value Type="Lookup">' + _spUserId + '</Value></Eq></Where></Query>',  // query
        '<ViewFields><FieldRef Name="ID"/></ViewFields>',  // viewFields
        '1',  // rowLimit
        '<QueryOptions><IncludeMandatoryColumns>FALSE</IncludeMandatoryColumns></QueryOptions>'  // queryOptions
    );
 
if (items.status == 200) {
    var rows = items.responseXML.getElementsByTagName('z:row');
    var lastID = rows[0].getAttribute('ows_ID');
 
    //redirect to wanted page using quered last item ID
    //here i'm redirecting to DispForm.aspx of newly cerated item
    var url = GetRootUrl() + "Lists/CereriUtilizatori/DispForm.aspx?ID=" + lastID + "&Source=%2FLists%2FCereriUtilizatori%2FAllItems%2Easpx"
    document.location.href = url;
}
</script>