French problem

when you want to answer "merci", you can say "de rien" = (read this as if it is english) "der ree-young" (or "der hey-young" if you cannot make the 'r' sound in french)
"my pleasure" in french is "mon plaisir" = "mon (as in "monitor) plat (sounds like "flat" but starts with 'p', and without 't' sound) see-er"
in your case (responding to a guest who says "merci"), to mean "you're welcome", you can also say "je vous en prie" = "sher-voo-song-pri" (or pli if you cannot make the 'r' sound in french)

In Spanish, in response to "gracias", you can say "de nada"

de rien ou service

welcome! French is Bienvenue!

you're welcome in french is " de rien " ( der Ree-ang)