How do I see the WiFi password?

Search for "Keychain Access" on your computer - it's an application that typically hides in your Utilities folder. Every time a dialog box pops up that asks you if you want ____ to remember this password and you say yes, that entry gets stored here. Once you've opened it, click in the Search field in the upper-right corner of the window that appears and start typing the name of your wifi network - it should immediately filter down the list to all unique entries you've input when adding your computer to that wifi network and agreed to let it remember/save. Double-click on the entry that looks correct from your narrowed search results, and click on the little white "Show password" ticker box at that bottom of the resulting window. It'll ask you for your authorization (via your computer account password) - give it, and it'll show you that entry's password.

If you access the router through Safari, just click on the Safari menu at the top left of your screen. Choose preferences. Choose passwords. Log in and scroll down until you find the password you're looking for.