I probably sound really stupid but i cant figure out how 2 close an envelope?

I'm mailing my friend a ton of pictures and so i bought this envelope that's like thin card board. On the flap thing that your supposed to fold there's 2 little things on each side that looks like are supposed 2 b folded in. But it wouldn't work or make any sense 2 fold them in. So I need help :]. lol thx!I probably sound really stupid but i cant figure out how 2 close an envelope?
If it's silver fold it in and insert through hole and then unfold it but with pictures I would tape it.

freckles