First let me say I am NO network expert, and all of the directions I’ve found tend to be directed towards people who are familiar with networking- which I am not. I am familiar with computers, I’ve jailbroken and added aTV Flash Black without a problem, but networking is another story.
I am running Windows 7 with an AT&T 2Wire modem/router. I don’t know whether I’m supposed to have a “Homegroup” set up or not on my Windows 7 computer (I don’t)- or if that even makes a difference. All I know is that when I go into Media and try to ‘Add Share’ it does not automatically find anything on the network. When I go to “Other”- it asks me all these questions that I don’t know how to answer. AFP/SMB, Name, Server, Username, Password, Workgroup- I have no idea how to answer them.
I’m sorry if this makes complete sense to most of you, but it would be nice to have “aTV Flash for Dummies” or something for those of us who are not familiar with how to connect devices for streaming. All I want is to be able to browse and play videos from my computer to the Apple TV.
Since I’m clueless about this, I’m not sure what I should expect to see when I try to add a Share- should it find my computer automatically? Is it possible the 2Wire router blocking access?
I also have my computer set to automatically sign me on- I don’t use a password and it is set to administrator so I never have to type a password- I have read somewhere that if you don’t sign in with a password that can be a problem with establishing a network connection.
Thanks for listening and hopefully someone will take the time to explain this in plain, “Dummies Guide” English. 
-Taylor