How to add an id attribute

where to add that id attribute ,am confusing and i already spent more than 5 hours in this mistake ,can anyone help me,please?

they given there to add id in form but i already added ,you see there

please send me answer as soon as possible.

I added in css like this
#cat-photo-form {

take away in the form element the class attribute get rid of it

Yaa i already created the class of green-background in form but am asking about id ,please once again see that screen shot and tell me.

send me the link of the course… the one you are doing so i can do it…

NO you can tell me some hint i will try it.

take the class attribute just leave the id…

look i did it… you need to get rid of the class and