Fixing the down engerneered board behind first row

[Sonnypaul]

I shall be laying some flooring soon but want to find the best way to fix the board after my first row.

I'm running my first row off the hallway wall and running through to the new extension,

I'll be secret nailing the boards down.

Problem Ihave is the boards behind the first row can't be nailed down beacsuse it's the wrong way round, ie the groove faces out,

How can i fix these boards, glue? Screws?

Thank you

I will be plying the floor before aswell.

Only used samples for now to show as the flooring has not been ordered