Dear FreeSurfer team,

I have run recon-all and I have done smoothing in a sample of 24 participants which are divided into 3 groups. 
Now that I know which smoothing I would like to use, I am a bit lost regarding which of the files generated should I use and how I should concatenate them. It is my first time with FreeSurfer and I would much appreciate your help here. 
FreeSurfer version is the last release. 
I am working with Linux mint.
Merry Christmas,
Rosalia