First time installing Minecraft mods with Forge

make sure the Forge version matches the Minecraft version your mods were made for, that's the mistake almost everyone makes first. install Forge with the installer (client option), run that profile once so it makes the folders, then drop the mod jars into the mods folder in your .minecraft directory. a lot of mods also need a library mod to work, the mod page will list it. add a couple at a time, so when it crashes you know which one did it