This process as a whole is rather involved and assumes certain prerequisites, but I’ll answer your intimidate question…
Assuming you have the correct ISO, you need to first get its SHA1 hash (hopefully it matches the SHA1 listed in the fixlet; otherwise, take notice on why). Then rename the file to its SHA and copy to your BES server in \BES Server\wwwrootbes\bfmirror\downloads\sha1.
That will allow you to deploy the task, have the ISO cache on the BES, and then work its way through your Relays to your endpoints.
There is also a Staged approached and those filxlets are located on BigFix.me. Just search for Stage and you’ll see Stage1/2/3 fixlets.