There could be several problems...
1. There is nothing wrong with the original solenoid. Check to see that you have 12V going to the activation terminal when the key is in the start position. That would be the small gauge wire going to the solenoid. If you don't have 12V there, then the problem is elsewhere (from the keyswitch) and not in the solenoid. If you don't have a voltmeter, just take a small wire and jump from where the battery cable connects to the solenoid to the small post on the solenoid. You could try this with either solenoid to see if they work.
2. If the new solenoid has two small posts and you may have the keyswitch wire hooked to the wrong one. Some solenoids have the second post to supply 12V to the ignition system for starting.
3. You bought a solenoid that has two small posts, but one of them provides a ground for the solenoid coil. You'd have to run a ground wire on that second post. Those aren't too common, so you probably don't have one of those.
4. The solenoid you bought is no good or wrong for the application. What did you ask for?? If you're not concerned with originality (which, at this point I don't think you are), just ask for a late '60's Ford solenoid. Say a Mustang...any engine. It will have the two small posts, but you will only need to use one of them.