You’re looking for a Mexican.
Talking to the bartender doesn’t bring you any further. Talk to the man at the table. Investigate his proposition and accept his request. He wants you to get a red bottle from the winecellar. Walk outside and talk to the bum. He wants the same.
Walk to the north and into the alley. The door on the left leads to the winecellar but is locked. Use your gun on the door to shoot the lock and use the door to enter the cellar. Walk to the left into the cellar past the first shelf. There you can see a shiney object on the floor. Pick up the smooth object to find it’s a MIRROR. Walk back tot he right. Use the mirror on the barrel next to the entrance and the light is reflected into the cellar.
On the second shelf is a RED BOTTLE. Take it and leave the cellar again. Walk to the north to leave the alley. From here there are two scenarios to reach your goal.
Senario 1 – The bum cooperates:
Give the bottle to the bum. He’ll give you the KEY to his room. Enter the saloon and use the stairs on the right. Look at the door on the left. Your target is behind it. But the door is locked and he doesn’t want to come out. Use the key on the door on the right and once inside use the window to climb on the roof. Walk to the right and use the window on the right to enter the room of the Mexican.
When he asks what you want, it doesn’t matter what you answer. The mexican will make you an offer. Wether you accept it or not, the Mexican will die either way.
Scenario 2 – The force is with you:
Enter the saloon and talk to the man at the table. You’ll give him the bottle and he’ll give you a stick of DYNAMITE. Use the stairs on the right. Look at the door on the left. Your target is behind it. Use the dynamite on the door to gain access and talk to the Mexican. When he asks what you want, it doesn’t matter what you answer. The mexican will make you an offer. Wether you accept it or not, the Mexican will die either way.
Game source: A copy of the game was found here on the internet.