Can you find a bit sticking up from the top of the shape, like your little finger? That's Thomas' black funnel, where the steam and smoke comes out. After all, Thomas is a steam engine - that means that rather than using petrol, or diesel, or oil, or even electricity, as cars and trains do nowadays to move along, Thomas has a fire inside, that heats water inside him like a kettle. The steam that's made when the water boils makes Thomas move.
When you've found his funnel, move your fingers down a bit, and just a little to the left. You should find a big curve - it's the side of Thomas' face. In the middle of his face is Thomas' big bobbly nose, with his round eyes on either side. You might be able to find his smiley mouth, just underneath his nose. He really is a cheeky little engine!