How do I add the form to my website

That mostly depends on your website, since there are various ways to do so.

In general the best option would be to use iframe embed method, for which you can see how to get the code here: How to get the jotform iFrame Code

Now if you are using some more known CMS we most likely have the instructions / guide for it specifically, so you can check all of them here: Share Forms, but if you wish, just let us know what system you are using - if you do not know we can sometimes tell by looking at it - and we would do what we can to assist you with the embedding of your jotform.