>>sfmike+(OP)
I'm afraid I'm not aware of any how-to guide. City/County/State tend to be harder; federal court dockets are all uploaded to PACER (
https://pacer.uscourts.gov/) which has fairly good search options, though be advised that there's a usage charge. Lots of stuff then gets uploaded to RECAP (
https://www.courtlistener.com/recap/), but it is inherently less complete than PACER, though if you do start using PACER, I strongly recommend installing the RECAP browser extension as that will upload any documents you view to RECAP, as well as advise you when a copy is already available on RECAP.
For what it's worth, this one was:
1. Find the DoJ press release (I think this was just Google search for a few keywords)
2. Accidentally notice that the press release said that the plea agreement had been filed in court
3. Open the court's PACER instance, and search for the defendant's name
4. Open the docket for the case, and download the plea agreement
5. Skim through (ignoring the factual background since I was looking for the sentencing information)