since I just woke up and you just posted this I'll toss in a comment but
I'm by far no expert in DNA (I've CC'ed Gary Felix - Hi Gary. . .Feliz
Navidad - of the Mexico DNA project to comment if I totally miss the
boat on something: very possible):

to help your genealogy along using DNA you want to work with a Y-DNA
work up which is the one passed along through male individuals from
father to sons. mt-DNA is passed on from the mother to both sons and
daughters. So you can do your Y and mt DNA, but from my understanding
Y-DNA is much closer in time span to our present time while mt-DNA skips
back many many thousands of years back so it is harder to find a match
with someone who you can prove is your relative via a written document.

So what you do is have the 25 or 37 marker or even the next one 67?
marker test (the more markers the more likely you're a match if both
indivduals test the same). And you use it to compare first with
indivduals that have the same surname and you