What diagram to begin with when starting a website from scratch

I want to start building a strong website in a professional way .. So in my first step i gathered data from the client but as a developer i want to be sure that i got all what he need to do so searched and found that UML can help me in this .. but i found a lot of diagrams ( USE CASE diagram, CLASS diagram, SEQUENCE diagram .. etc ) ..

after i searched a lot more i found that not all diagrams will be understood by the client i found that use case, sequence and interaction diagrams will be more helpful in this stage

So my Question what diagram to begin with and are they all important to do or can i use one of them and it can offer me all i need and if so can you help me with a reference ?