First, a little info & disclaimers about blocking:
So, your best way to ensure your privacy, in summary, is to have a private page (click here to learn how to alter your privacy settings) and block people on top of that if it is necessary.
It's very simple to block someone.
Step 1 Go to the blue header at the top of your Facebook page and either
(a) click Settings, or (hover over Settings and wait for the drop-down
(if you don't know what that "hover" means, it means to let your mouse rest over that word Settings. whether you clicked or hovered you will be fine)
Step 2 (a) If you hovered, you will see this drop-down, click Privacy Settings
Step 2 ( If you Clicked on Settings you will see this page, click "Manage" next to "Privacy"
Step 3 Under "Block List" either type the person's name or their facebook-registered email address in the fields provided (you can try their various email addresses until you get the right one, don't worry, nothing will happen--no notification or anything is sent to them)
Step 4 Click "Block" button
Step 5 A window will pop-up asking you to select the correct person (if there are multiple Facebook profiles with the same name, for example) that you would like to block.
And you're done!! Your Block List should show that person under it now. (yay! that paris hilton has been bugging me! yeesh! jk)
And if you would like to REMOVE them from your Block List, simply... click "Remove" next to their name under the Block List.
And POOF! they are removed from it. Again, if they were your friend and you Blocked them, you will need to request their friendship again to restore them as a friend on Facebook.
Yes, very informative and it's good to know how to get out of "sending a friend request in error"
Wellington Florida
Married
Great tutoral!

This is also really handy if you do a stupid thing like I did once and send out a invite to someone on accident. You can't un-send a invite but if you block them it removes the invite. Now they might get a email saying that you sent them a invite but it wont be there. Like you said they will not get a email saying you blocked them. I had a panic attack one night when I did this - duh