Look, you don't know what DDOS is, its gonna take a lot of research and resources to do anything that would impact any large corp, no less a guberment.
Step 1 get lots of computers and lots of friends or bots.
Step 2 ping (not really) whoever you want to ddos with all the bots and pcs.
You'd be surprised as what buildings are data centers. They usually look like a warehouse. There's several all over the place. I would guess at least 5 in each major city, Sacramento, SF, LA, and so on.
But trump can keep classified documents in the bathroom...