Lewis structures are a way of showing bonding between elements using dots or lines to indicate valence electrons. A dot represents one electron and a single line two electrons. Two electrons form a single bond. You can also have a double bond between two atoms which is indicated by four dots or two lines. In some cases elements will also form a triple bond which requires 6 valence electrons (6 dots) or 3 lines.
In your question, the molecule is cyclohexane. The name tells you everything you need to know. Hexane indicates there are 6 carbon atoms in the molecule. The -ane ending indiates that all the bond between the carbon atoms are single bonds. And the cyclo tells you that the 6 carbon atoms are located in a ring structure. So if you draw a hexagon and put a carbon at each point that is the basic structure. Look at the drawing and you will see that each carbon atom is bonded to two other carbon atoms. But carbon has 4 valence electrons. That means that each carbon atom also has two hydrogen atoms attached to it. So add two hydrogen atoms to each carbon in your drawing - using either two dots between the carbon and hydrogen or one line between the carbon and each hydrogen - and you have the finished lewis structure.