Okay so to work out the surface area of any 3D shape, you should look at the area of every surface on the shape individually. I would then draw a cylinder. First, we can work out the area of this circle (I would label a circle from the cross section of my drawn cylinder), which is pi * r squared. Now, we will work out the area of this shape here (I would label the panel in the middle). In order to do this, we multiply the circumference of our circle by the height of our cylinder - so we get pi * 2r * h. The last surface is the same as the first one, so is just pi * r. Finally, we add all of these together and have our answer.
One thing I struggled on particularly at GCSE was remembering the equations for area and circumference of circles - until I found this song which springs into my head whenever a question pops up like this: 'https://www.youtube.com/watch?v=zuV1puxGMZQ'.