Most backpackers use a free web-based email account when they're on the road, although you can also access your regular email account. There are hundreds, perhaps thousands, of companies which offer free email addresses. You can log on from the bug.nu home page or from bugmail.net . You can also check your regular POP3 email address from your bugmail.net email account, although you will need to make a note of your email program's settings first. It is best to try checking your POP email before you hit the road to make sure that you've entered the settings correctly.
Most hostels have Internet access, although some are rather expensive coin-operated terminals.
A more traditional way of keeping in touch is good old regular snail mail. It is pretty straight-forward to send mail. Just take your letter to the post office and buy a stamp. Just like home. In some countries, such as France, you can buy your stamps from multilingual vending machines and avoid the queues at the post office.