Matty Fryatt grabbed the only goal in the 64th minute as Forest`s remarkable 36-match unbeaten home run was ended.
Harper told the club`s official website: "It was a scrappy 1-0 win and it was a battle.
"But we did well and we had a great set of supporters on the day. They turned up in big numbers, sang their hearts out and got right behind the boys, so that win was for them really.
"It was hard work and it was all hands to the pump but we feel like we really earned that win.
"They were really coming at us late on and we were blocking everything. I don't know what was going on but I just wanted the whistle to go. It was a bit gutting that other teams around us got results but we'll crack on."