Hello,
Where do I write to get the birth certificate of my deceased aunt, Bella Weil, born 12/07/1908 in Algrange?
Thank you
Nurit Hirsch

You need to go to where they keep the vital statistics in your area.

Type vital statistics algrange in the search engine to see if it helps any.
Here in the USA it is somewhere like the State office building usually.
Also if it was not mandatory to keep records back then she may not even have one.
Some people born in that time have to use baptismal records.