Answer :

Bonjour Monsieur
OR
Bonjour Madame
just to say hello or welcome him ?
Je suis heureuse de vous accueillir parmi-nous, soyez bienvenu !

(I am happy to welcoming you among us, you are welcome!)

you just ask how they are for example
you- Bonjour! ca va? (hello how are u?)
person - bonjour ca va bein merci etoi? (hello I am well thank you, what about u?)
you- ca va bien (im good)/comme ce comme ca (im okish) /non, pas mal(not not good)/mauvais(bad)
person- pourquoi?/pourquoi pas? (why/why not)
you- je suis fatigue(I am tired)

and then 'auivoi' (bye)

im not saying you have to feel bad on that day, this us just an example lol
by a 14 yr old french GCSE student xxx