You won't lose any mods or configs if you only uninstalled the game through steam and you didn't touch the appdata folder.
If you did you need to open the userfolder of the old computer, and copy the mods from here to an usb key, then paste to the new computer. You can always try to install the game to see if you're automatically subscribed to them befor emoving the mods.
From my own experience, if you have the game on Steam, it will automatically redownload all the mods you've been subscribed to, even if you remove the appdata folder, but you're obviously going to lose everything else