Draw your molecules on the paper. Draw a hexagon with three alternating parallel lines in its center, indicating benzene's shared electron bonds. Draw sulfuric acid, an "S" with three "O"'s around it, connected by double bonds, drawn as parallel lines from the "S" to each of the "O"'s.
Draw an arrow from one of benzene's shared hydrogen bonds to the center of the sulfur molecule. Because the oxygen pulls electrons away from the sulfur, the sulfur then wants to pull electrons from another molecule, which in this case is one of benzene's electrons. This creates a single bond between the benzene ring and sulfur molecule. Draw an arrow from one of the double bonds between the "S" and "O" to the "O," indicating the the oxygen is now negatively charged. It has an extra electron.
Draw the result of the ion movement: A benzene ring with one of its points positively charged and a new bond between the next closest point connecting the ring to the sulfur. Draw a small negative sign by the "O." Even though there are two ions, one is positive and one is negative, making the molecule neutral overall and still stable.
Draw the three structures that have equal potential to be present due to the ease with which benzene can transfer its electrons around its ring. Draw an arrow showing one of the double bonds left in the benzene ring moving directly across from the other double bond still left, moving the positively charged point directly across from the point where sulfur has bonded. The other double bond in the benzene ring can also move to fulfill the positively charged atoms need for another bond. This final proton movement lands the positive charge at the point adjacent to the sulfur bond, just opposite where it began. The molecule can just as easily go back to its original structure. This shows that the molecule is constantly toggling between the three structures.
Draw an arrow from the oxygen toward the hydrogen sharing a carbon with sulfur on the benzene ring. The negatively charged oxygen has a strong pull and wants to be neutral overall. It takes the positively charged hydrogen. This causes an electron to fold back down into the benzene ring, fulfilling its needs to have 12 electrons total. It is now stable. The benzene ring is now sulfonated with sulfur now having two double bonded oxygen molecules and an alcohol group (oxygen plus hydrogen).