7 Card Stud Hi-Lo is played the same as 7 Card Stud as far as the dealing of the cards and the betting goes. The difference between the two games is only in the showdown and the end of all betting.
As the name suggests, there can be 2 winning hands in which a pot is evenly split between the winning high hand and the winning low hand.
In order to win the high hand, you must have the best 5 card poker hand of all the players that remained in the hand. To win the low hand, you must be holding the lowest cards which must be 5 different denominations of cards lower than 8. Ideally, and A-5 straight is the best low hand to hold.
If no player qualifies for the low hand, than the entire pot is awarded to the player with the best 5 card poker hand.