TYTONK, tell me
exactly where you are and I'll tell you what your problem (probably) is and how to fix it. I'm guessing you either can't find the "invisible archway" into BG City itself (a very common problem) or you just plain don't know which maps to walk through to get to the city. Happily, you say your Journal says Chapter 5, so we know you did the Cloakwood Mines right, and you won't have to Reload/edit/yada yada yada.
How To Enter Baldur's Gate For Dummies:- Kill Davaeorn, read the important notes in his locked chests, take the elevator to the first level of the Mines.
- Flood that sucker.
- Leave the Cloakwood and go back to the Friendly Arm Inn.
- Take a bath. Two, preferably.
- Go north.
- Keep going north until you see a bridge.
- Cross the bridge.
- A guy named Scar will ask if you were responsible for the "fiasco" at the Nashkel Mines. You might choose to tell the truth, you might choose to lie. The truthful answer is "yes."
- A road leads to the western end of the bridge. Follow that road.
- Where the road meets a stone wall is the imfamous "invisible archway." Walk back & forth in front of it until you can see the ground on the other side of that wall. Mouse over that patch of ground until you get the "wagon wheel" icon that means you can travel to the next map.
- Welcome to BG City. Get ready for about 3 dozen quests, all at the same time.
- Bow down to my encyclopedic knowledge and infinite wisdom.
- Take the link in my sig and read the Guide. Reading good. Especially Chapter 13 (I think it was Chapter 13.....)