If you're talking about modloader, Find modloader's download button, and download it. Wait for the download to finish, and you have downloaded it. As for installing it, that's a completely different topic. Usually following the instructions on the page will help.
It's actually a simple process actually. Though it does take some explaining. Go to the minecraft Wiki for details about that, took me a minute to find that information.
On YouTube there are a few good explanations but the best way to find one is to ask for a specific mod, Death chest for one, and they will give you a good description about it. If you want anything else about the topic just msg me.
You get Terraria from steam. You can also get other games like Elder scrolls 5 Skyrim and Minecraft.
The Server has to install the mods Not You.
bearshare is not required to get minecraft mods.
You can download minecraft plugins from planet minecraft minecraft forums bukkit (for multiplayer) mods for minecraft.com mods for minecraft.net
minecrafts popular servers are pixelmon mods
No! Mods are short for modifications, which change the gameplay slightly. They aren't illegal, they just support only the version of Minecraft they are compiled for. Jeb is even thinking of adding "Mod Support". Although, If you are playing on multiplayer servers, you should check the rules because some servers ban certain mods/hacks. Some servers even require you to download certain mods and/or texture packs to log into them (Tekkit servers, etc.)
you can get most minecraft mods off the minecraft mods website, or you can google.
download it then chuck its contents in a mods folder in minecraft .jar
no
Minecraft mods are always free.
You can still add mods using a different launcher through Demo/Single player you just can't join multiplayer servers. You have to purchase a premium account for that.
Depends on your server host.
go on you tube