How to edit a website with only the domain name, user id and password

I was hired to make changes to a website so I asked the person who made it to grant me access. She gave me this HOSTING: http://www.example.com/ User name: user1 Password: password1 I asked her how to log in and told my client to tell me to stop bothering her and that he should hire someone who knows what they are doing. I tried using those credentials in filezilla but had no luck. How can I connect to the host to edit the files?