Pick one of Arachne's linearts shown in the challenge thread and colour it (don't forget, colouring also means texture/shading etc... too!). Also, make sure you give your newly coloured creature a background.
Links to challenge lineart -      
Canvas Size - Maintain the original canvas size. You may flip/rotate the canvas 90° if you like.
Colours - Unrestricted.
Transparency - No.
Animation - No.
The challenge thread will have all the challenge updates. The thread is also a great place to post your WIPs.