Hello Isabelle,
I didn't receive your e-mail info, but not important. Dial up the following on Google:
FTDNA Surname projects
then dial in the surname you require, eg Devereaux. Bear in mind that you need a male to test of that surname for Y-DNA tests. I recommend 37 markers as the minimum
There is a group for the surname Devereaux you are interested in, so that will keep the cost down! Y-DNA only applies to father-to-son relationships, as you are probably aware. Mother-to-mother is covered by mtDNA.
Happy hunting,
Bob