In the age of email and texting, writing a handwritten letter is a thoughtful way to show someone you're thinking about them. However, it takes a little more effort to mail a letter than it does to press "send." If you're unaccustomed to using snail mail, you may be confused as to how to make sure your letter gets to the right place. You can ensure this by writing the address correctly, and using appropriate postage.
If you live in the United States, you'll notice blue USPS mailboxes bolted to the sidewalk in cities and suburbs. You can walk to one of the boxes, open it with the handle, place your letter in the slot, and close it. A postal worker will collect your letter and start the delivery process.
Why not surpise someone you love with sending them a letter? Beware of muggles.