Look for a flag toward the right end of your menu bar. Click it to open this menu:

Click the Show Keyboard Viewer to open the Keyboard viewer.
Press either of the Option keys to view the characters available with the option-(key) combination.
The five keys highlighted in orange produce 'combining' characters—accents that can be applied to a number of letters. Option-n, on the Canadian English keyboard layout for example, places a combining tilde ( ˜ ). To write "cañon" you would use these keystrokes (without the spaces): c a option-n n o n
Keys showing an accent or other symbol, but without the orange highlight, place 'regular' characters, as opposed to combining characters.
If no flag is showing in your menu bar, go to System Preferences > Keyboard > Input Sources, and check the "Show input menu in menu bar" checkbox.
Regards,
Barry