How do you draw chair conformations?
There is no substitute for using models.
In the diagram, the axial methyl interchanges position to give an equatorial methyl group. All of the groups on the left hand side exchange axial and equatorial positions with respect to the right hand side.
You need to manipulate suitable molecular models in order to appreciate this conformational change, and you need to practise how to represent this change on the printed page. It is a non-trivial exercise. Good luck!