How many people celebrate remembrance day?

They wear it so that people remember the people who died, because when people died on the field, poppies started to grow all around.

I think you mean where abouts on the body? In the UK; females should wear it on the right side (as this is where war widows wore their husbands medals) and males should wear it on the left. The leaf should be pointing at 11 o'clock to signify the 11th hour of the 11th day of the 11th month.