Palace won the first-leg 1-0 at Selhurst Park last night thanks to Jean-Philippe Mateta's goal.
Glasner said, “Goal number one is winning the game and if you wish something, you want always to win four or five-nil, but we could see it’s not so easy.
“The game was exactly how we expected: Frederik playing very deep, defending the box very well, so we had, I think, four or five very good chances. We hit the post twice, so we were not that efficient, and then it's not that easy.
“But at the end it's important, taking the win, first game in Europe and winning. We’re still at the start of the season, and the second time in a row having a clean sheet is also important, so we are on track.”
System surprise
Glasner admits Fredrikstad surprised him with their system at the start of the game.
He also said: “We expected them (Fredrikstad) in a 3-5-2, or 5-3-2. No, it was more 5-4-1 – very deep.
“And then I think after 15, 20 minutes, we changed a little bit. We wanted either Justin Devenny, like a No. 10, playing more in a 3-1-6, and Will Hughes overloading the left side and then getting more players in the box.
“It was difficult to find space in the pocket. There was no space, so it means you have to come from the wing, and this then worked better. We had a big chance with Ismaila Sarr.
“And then it's when they dropped with all their nine or ten players into the box, then we have Marc (Guéhi), who can play great crosses. We had Adam with a few good crosses. We had finishes, but we didn't score.
“Then we said: ‘OK, stay patient, keep going’. And at the end, JP's head was somewhere in the way and deflected the ball.”