You are able to check this out the Fallout 3 Wiki for materials concerning how to install mods in Fallout three: I'm unsure what mod manager you are using. In Steam you can simply click on "Install Game" and it will download the mandatory files. I haven't played Fallout 3 in ages, although I do think you're supposed to be able to do it throughout the launcher, also. The most used mods that we...