Eutrapelia,
(nice nickname btw, I trust you have the idea of its meaning in its
original language :))

Assume the year is in A1 and in B1 you put a number from 1(Sunday) to
7(Saturday). The following formula will return the first day of your B1
choice:
=DATE(A1, 1, MOD(7-DATE(A1, 1, 1)+ B1,7)+1)

HTH
Kostis Vezerides