E-commerce accept terms and conditions, any clue?

Hi Guys,

I am new to CI and I need to build a "terms and condition agreement" for a e-commerce website where the user will mark a checkbox after reading and agree with the contract. After that the user will be redirect to a view with a "buy" button

I have searched online for such thing but I couldn't find any good explanation for that.

Have you ever develop it before ? Can you help me ? Point me to the right direction ?

I am looking for a modal window where the agreement will be.

Thanks