Do you want instances of the account class to be assigned, or mapped to strings? For example, john is mapped to an account object, victorious to another?

The solution that comes to mind is to use the dictionary object, which is a hash table that allows you to associate objects of arbitrary type to string keys. For example,
dictionary accounts;
Account johnsAccount;
accounts.set("john", johnsAccount);

Then you can check for whether such an account exists with accounts.exists("john") and retrieve John's account if it exists.

Note that keys may only be associated with 1 item per dictionary.

you would have to do something like
class account {
void create(string username, string password) {
//create account here
}
}
account@[] allAccounts;
void main () {
//check if the received packet has create account in it, and if it does, then
}accounts.insert_last(account);
accounts[accounts.length()-1].create(username,password);

class account {
void create(string username, string password) { //this method from the server creates the account with the username and pw.
//create account here
}
}
account@[] allAccounts; //an array of account object handles. This array stores any newly created accounts as well as any accounts you would load if someone had logged in.
void main () {
//check if the received packet has create account in it, and if it does, then
}accounts.insert_last(account); //creates a new account object in the accounts array.
accounts[accounts.length()-1].create(username,password); //initializes the account in the last array slot with the user name and password that you parsed from the network request.
}
note: you can't make variables out of the strings you parsed from the network request, because that's just not how it works. A variable name is just arbitrary. That's why you have to create an array of account objects. plus, once you have like 400 accounts, managing each one by its name would suck anyway. You could create a function that returns an account object so that you could more easily deal with them though, something like
account@ get_account(string username) {
for(uint x=0; x<accounts.length(); x++) {
if(accounts[x].username==username) return accounts[x];}
}
return null;
}

So I've gone through and worked it all out in my head and I believe this solves my problems just fine. The only thing I'm having a hard time deciding is if I want to put my movement code, weapon code, and collision code  in the account class, or if I want to have the functions run forloops with the accounts. From my understanding this problem pretty much equates to deciding if you should write 2+3=5 or 3+2=5. Is there a factor that I'm just not thinking of that would determine which direction I should go with this?

Alright. So I have my create account code working. Now I've just got to figure out how to save these accounts and load them later. I know I have to serialize everything, but I'm having a difficult time understanding the process describe in the help files. Maybe I'll have better luck if someone explained it to me.