how to type alt code symbols on my keyboard and on to a email or FB

In System Preferences > Keyboard > Keyboard, check "Show Keyboard & Character Viewer in menu bar."

When you want a special character in the text you are typing you can now click on the keyboard icon on the right side of the menu bar and select Show Character Viewer. You can browse through the various selection options. When you find the character you want just double click on it and it will insert into your document or email text.

In most applications you can type command+option+t to open the Character Palette. The command key is the key with the apple () or clover (⌘) on it.

Type "heart" in the search box at the bottom of the Character Palette. Here are some of the results...

Black heart: ♥

White heart: ♡

Heavy black heart: ❤

Rotated heavy black heart: ❥

Floral heart: ❦

Select the heart you want and then click the "Insert" button. The heart will be inserted into your current text.