Vizuna square
Greaeger
How do i get in there? Ive notised several doors that i cant get past, do i have to finish some quests for those or what? plz tell me how 
Marty Silverblade
Depends on whether you're Canthan or not. Canthans must complete 'Mayhem in the Market' (I've never actually done this so don't ask for too much info), and Tyrians and Elonians must complete 'Welcome to Cantha'. Otherwise you won't be let in.
Also, if you're Tyrian or Elonian, you will be directed to Visunah Square (Foreign Quarter), and Canthans will be directed to Visunah Square (Local Quarter). It is possible to get into both, just join a team that is doing the quest you need (i.e, Canthans join a team doing 'Welcome to Cantha', and Tyrians/Elonians join a team doing 'Mayhem in the Marketplace'). Although you won't have the appropriate quest, other people will and they can teleport you inside. It's sort of like taxis to elite missions...
Also, if you're Tyrian or Elonian, you will be directed to Visunah Square (Foreign Quarter), and Canthans will be directed to Visunah Square (Local Quarter). It is possible to get into both, just join a team that is doing the quest you need (i.e, Canthans join a team doing 'Welcome to Cantha', and Tyrians/Elonians join a team doing 'Mayhem in the Marketplace'). Although you won't have the appropriate quest, other people will and they can teleport you inside. It's sort of like taxis to elite missions...