Artist wrote:

えっ・・・！これを挟めって？

わ、わかりました。やってみます・・・！

stick it in between
just try it

Artist wrote:

えっ・・・！これを挟めって？

わ、わかりました。やってみます・・・！

I'm not quite experienced in Japanese, but here's what I get:

Eh...? "Insert this one [between]", you say?
I... I got it. Will do it.