Getting into Time CapsuleIs is easy, there is an icon, or should be, in your menu bar that looks like a clock pointing at five o'clock with a circle around it.
Depending on what time machine finds when you click on that icon you will see different options.
In your case you will want to click on Enter Time Machine.
Or you will see an icon that looks like this in your dock.
Clicking on that would take you to the same place.
Your screen will change to show you this.
If you have mail open when you enter Time Machine it will make it easier to locate those missing e-mails.
It can take some digging around to find exactly what you're looking for but it is there.
Once located highlight what you want and click on restore at the bottom of the screen, then follow whatever prompts it gives you.