When i drag a mod to horizon, an error comes up

Invalid signature type detected for the loaded package. Halting reading. Please make sure the file is a valid Xbox 360 XContent Package (‘LIVE’, ‘PIRS’, ‘CON’)

how do i change the mod so it can be valid?

What do you mean by mod, a modded game save? If it’s a save you downloaded online there’s a good chance it’s in a a zip or rar container, you need to remove the file(save) from the container before attempting to drag it into Horizon.

Give us some more info and we will be able to help you.

Are you talking about dvar mods or more like mod menus?