Lookup method in Form level 

public void lookup()

{

    Query                 query = new Query();

    QueryBuildDataSource  qbds;

    QueryBuildRange       queryBuildRange;

    SysTableLookup        sysTableLookup;

    ;

    sysTableLookup  =   SysTableLookup::newParameters(tablenum(CustTable),this);

    sysTableLookup.addLookupfield(fieldnum(CustTable,Name));

    sysTableLookup.performFormLookup();

}