You could try something like this
obviously set the location, to the location of your sign, and change it to whichever line you would like

Code (Skript):

1. on load:
2.     set {login.count} to 0
3.  
4. on join:
5.     add 1 to {login.count}
6.     set line 1 of block located at 0, 0, 0 in world "world" to "%{login.count}%/100"
7.  
8. on quit:
9.     subtract 1 from {login.count}
10.     set line 1 of block located at 0, 0, 0 in world "world" to "%{login.count}%/100"
11.  

 

sorry i typed it wrong

Code (Skript):

1. on join:
2.     add 1 to {login.count}
3.     set line 1 of block at location at 0, 0, 0 in world "world" to "%{login.count}%"
4.  
5. on quit:
6.     subtract 1 from {login.count}
7.     set line 1 of block at location at 0, 0, 0 in world "world" to "%{login.count}%"
8.  

 

try log out, restart your skript, then log back in

 

Im sorry I do not quite understand what you are saying, but if you are meaning if they click on a sign in TPs them somewhere,
try this

Code (Skript):

1. on right-click on sign:
2.     if event-location is location at 0, 0, 0 in world "world":
3.         teleport the player to location at 0, 0, 0 in world "other world here"
4.