How do i Get to there if my Character cant reach? is there an Item i need?

Yes, two of course. The staff which breaks those blocks. And there are boots which gives you double jump.

Oh, ok. Thx!

what's the key?

Use your stopwatch whenever you feel stuck. The Lord would have told you the same thing like this. The key was re-posted the 8th time just yesterday. Learn to search for old post on Miiverse. It's so easy, even a caveman could do it. Just 28 posts down.