Firstly, as the Kanger Evod is a bottom-filling tank, please ensure that you keep it upside-down (mouthpiece down) whilst refilling.
Remove the base of the tank by unscrewing the silver-coloured ring, then insert the tip of your e-liquid bottle down the side, avoiding the middle tube. If you look through the window in the side of the tank whilst you're filling it up, you'll be able to see the metal tube in the middle - avoid filling the tank higher than the top of this tube otherwise your e-liquid will spill out.
Finally, re-attach the base of the tank (including the coil).