Okay. There are a number of security systems employed by banks to prevent you from doing exactly what you want to do, which is steal money. You're going to have to work to get exactly what you need to rob a bank, you can't just start now.
First, you want to just do normal, easy missions until you get $20,000. Don't spend money on anything other than v4.0 of the Trace Tracker and Log Deleter. Once you get $20,000, buy a HUD_Connection Status upgrade. This is a very important little screen. Continue saving up until you can get a $25,000 Monitor_Bypass v5.0. This will let you crack passwords and get through firewalls and proxies without being traced. Save up again, and get a $20,000 Proxy_Bypass 5.0. Finally, get the $10,000 Firewall_Bypass 5.0. Another thing you want is a Decypher (not Decrypter) v3.0 for $8,000 for taking down Elliptical Curve passwords. Once you've got all that, you can get into just about anything without being noticed.
Anyway, back to the bank's security systems. First you have to make an account for yourself, which I assume you have. Then you have to find an account to steal from, preferably one with lots of money. Once you find the correct account, go to the login screen for that account and type the account number in the "Name" field. Enable your Monitor, Firewall and Proxy bypasses now. Then use the password cracker on the password field and it'll find that account number's password. If you did everything right, you should have full access to everything in that person's account and you won't even be noticed. Transfer the money from their account to yours, delete the statements, delete the statements in your own account, and delete the logs from your first hop (should be the Uplink Test Server or InterNIC).
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Hard work never killed anybody, but why take a chance?
-Edgar Bergen