Javascript "Math Test"

I want to make a simple math test with a choice of easy or hard problems, that are randomly generated. Easy would be addition with numbers up to three digits, and hard would be the same thing or have a multiplication problem with numbers up to 2 digits. the user can pick easy or hard, and should be able to pick again while looking at a problem. and finally a text box with a submit button to check the answer. i have to do this for my class and im completely lost, so any help would be greatly appreciated.

p.s. i dont necesarily want you to do this form, maybe just some short snippets of code with an explanation of what each do.