And what better way to start than wishing you all a very big "welcome" to this account? (The Portuguese word is literally composed of "well-come" / "well-comers")
Unlike the English word, the one you see before you is conjugated to the plural (as writing to an "audience", or readers: hopefully more than one!) and also the masculine. The plural masculine is not only used for a group of men, but it's also used for a mixed group of men and women.
In case of a group composed only of women you say "Bem-vindas!" instead.
If you want to refer to a single person subject:
Bem-vinda! (in the feminine)
Bem-vindo! (in the masculine)