Gardner made the move from Birmingham City during the week.
"Bringing in players like Seb and Connor Wickham shows the club are going places," he told SAFC TV.
"We want to finish as high up the table as possible and towards the European spots.
"I really believe Europe is a realistic goal for us.
"The club aren't spending on older players; the manager is bringing in young, hungry lads and that's what it's all about."