Spit in the tube and wait for your tree.
It’s not as simple as that.
Autosomal DNA test results indicate a relationship. If the relationship is close (sibling, parent/child, aunt/uncle, first cousin), the predicated relationship is usually easy to immediately determine.
But beyond that it is not so clear. Based upon the amount of shared DNA, the precise relationship can be “roughly” determined, but research in paper records, interviews with relatives, and other “non-DNA” research is necessary.
The DNA is only part of the story and spitting in a tube doesn’t mean your ancestry will be spitted right back at you.
It’s more difficult than that.