How to make one note last longer than the others?

[607]

Hello, I'm currently arranging Snow Land, from Mario Kart: Super Circuit.
There are some things that seem hard to write, but achievable to play. A relatively simple example is this one:

I'd want to make the selected (orange) note last as if it was a full note, while the other notes from the chord should remain chord. How would I write this?

[daj]

I would bring the note to layer 2! ^^ Another alternative is to tie just that note over, but that's lame.

[607]

Okay, thanks. I'm still not sure on how to do some parts, but I think for now I'll leave it as is or make some notes, as I'm not intending to release this at the moment, I would just like to have a way to learn it.
I'm planning to create a topic here after my exams, asking for help getting some of my older arrangements into NSM-quality sheets. Most of them are just a bit away from it and I haven't ever really cared, but as a means of 'giving back' I'd like to help getting some more sheet music of certain games on the site.
I'm not too confident on it though, as I feel like I don't know a lot about music, although I do compose chiptunes and play piano. But I'm quite sure some of you will be able to help me, and I wouldn't mind to learn! That is, once I'm done with secondary education: exams come first.