Halo Reach Mods
Much like my hub on Halo 3 mods and modded maps, this hub is for providing information on mods for Halo Reach. On the last hub, many people commented providing ideas for new mods. Please keep doing that--there are a lot of good ideas out there. The more we write them down online, the more likely it is that some techy will stumble upon it and make it happen.
Buy Halo: Reach at Amazon.com
Where to Find Mods
Here, you'll be able to look at a huge number of maps posted directly by the bungie community. There are thousands of maps, all organized for your convenience. The consistency of quality among these maps is definitely limited, but if you search through them enough you're bound to find a few worth showing your friends. All you'll really need is your information you use to recover your gamertag online. If you don't know this stuff, ask your Dad. There is an in depth description of how to download these maps on my Halo 3 mods hub. Go check it out if this didn't help you enough.
This website is pretty fun. It offers modding software created by the halo community. Don't go too crazy downloading every single program. Look at the threads posted under each person's specific file that they are putting out for use, they should be a good indication of whether the file is reliable or not. Also, most of the people who put their files on here offer pretty good instructions on how to use them. Follow them closely. Messing up while doing this kind of stuff can be extremely frustrating and time consuming. This guy had a pretty good review on his software. I suppose I recommend him. Here's his link:
Search every corner of the community files. Even if the maps on there aren't modded, there is an unbelievable amount of cool stuff you'll be able to find there. It's surprising how much time we've all put into Forge collectively. Hope this helps!