Okay,
1-Roms are technically illegal. You are "kinda" allowed to have it if you already own a copy of the game for "protection" purposes. This is why you don't see many legit ROM sites on the internet. Most are virus sites, but there are legit ones out there. My recommendation is to use Torrent sites and use BitTorrent to download ROMS, again still a little dangerous but depending on the site you can read peoples comments and they are generally truthful.
2-To put the ROMS onto the phone, you need to do several things. First, plug in your cellphone using the USB cord into your computer. Second, from the drag down menu on the top of the Droid screen, there will be two options, one is for protection and the other for downloading, select the downloading and then select the anchor option. Now my computer tried to read it as a new piece of hardwar, cancel that option and select the portable drive selection from your "My Computer" on your computer. From there, you will have access to the memory card inside the phone. Just create a new folder called ROMS, and drag any ROMS from your computer onto that card. When you are done, close out, tell the computer to detach the portable drive, tell your phone to detach, and it will begin reading the card again.