How to use Wall-nut first aid & Instant Recharge in Plants Vs Zombies 2?

Hi,

       I don't know how to use Wall-nut First Aid which comes after level 15 in Wild West, Plants Vs Zombies 2.

       I don't know how to use Instant Recharge which comes after level 20 in Wild West, Plants Vs Zombies 2.

Please help me.

Thanks in advance for your replies!!