Answer
The complete Lewis structure is shown in the picture below.
Work Step by Step
For making the lewis structure from line structure, draw the lines as bonds and draw the carbon atoms wherever two lines meet or a line begins or ends. Draw the O and S wherever there is an O and S, and draw two lone pairs on the oxygen. The three oxygens are connected individually to S and the hydrogen in $SO_3H$ is connected to one of the Oxygens. Then draw enough hydrogen atoms to give carbon a total of four bonds.
