How to babysit for the first time, at a shop?

So there is this woman who wants someone to look after her 21 month year old girl. I was just finishing the Red Cross child Care class 2 days ago. The woman works in a coat’s shop and I am supposed to just help her out with the girl. I invited my friend to come and look after her with me.
I will be looking after her for 2 hours only and per hour I get 400 krónas:D