SortCriteria defines a SortOrder, which contains an attribute name and an order type (ASCENDING or DESCENDING).
Query query = new Query();
query.Select("c.lname, c.fname");
query.From("Customer", "c");
AttributeTest aTest = new AttributeTest();
aTest.Attribute = "state";
aTest.TestValue = "CA" ;
aTest.TestType = AttributeTest.EQUAL;
query.TestCriteria = aTest;
SortCriteria sort = new SortCriteria();
sort.Add("lname", SortOrderType.ASCENDING);
sort.Add("fname", SortOrderType.ASCENDING);
query.SortCriteria = sort;