How to add texture to hand-drawn artwork in Photoshop using the Filter Gallery
To add a bumpy texture surface to an illustration or sketch, and a real-media feel, head to the Filter Gallery in the Filter menu.
Select the Artistic category and choose the Rough Pastels filter.
Rough Pastels contains a variety of textures, including canvas and brick.
Keep Stroke Length and Detail sliders to around 4-6 and boost up Scaling under Texture.