Let us know how it works out.

Slide off the back cover of the DIR-506L and insert the provided Lithium-Ion battery. Replace the cover. Connect the provided USB cable to a source of USB power and plug the MiniUSB plug into the side of the DIR-506L and let it charge a few hours.
Once charged, turn it on using the slide switch above the power jack. On your wireless device, wait for a WiFi connection DIR-506L to appear. Connect to it - it doesn't require a password. If it doesn't connect right away, wait a minute and try again. Open a web browser and go to 192.168.0.1 . You can also use dlinkrouter.local (if you're on an Apple device) or just "dlinkrouter" otherwise. It should present the router login page. The User Name is already filled in as "admin", no password is required. Click Login.
Tap/click TOOLS in the strip that runs across the page. If needed, tap ADMIN in the left column. In the space for an administrator password, type in the password of your choosing. In the V2.11 firmware, this password must not be longer than eight characters - that will supposedly be lifted in an update. Tap Save Settings - the router will reboot.
Wait for it to come up again, reconnect and again go to the router login page. (You may have to reselect the DIR-506L SSID in your device's WiFi settings.) Log in using the password you set. Now tap SETUP in the top strip and then WIRELESS SETTINGS in the left column. Tap "Wireless Connection Setup Wizard". This is where you'll change the default of unsecured WiFi to a secured one. Tap Next to go through the screens. On Step 1, you'll name your wireless network. What I did here was pick a name different from my home wireless, but it might be convenient to just match your home wireless (as long as you didn't use the manufacturer's default!) On Step 2, select BEST to get WPA2 security. This is the only one you should be using, unless you have a decade-old device that doesn't support WPA2. On Step 3, select TKIP/AES for the key type (it isn't labeled as such) and then enter the WiFi password of your choosing. This should be at least eight characters - more is better. Tap Next and you'll be shown a summary screen with the settings - tap Save. The router will reboot again. When it's done, test that you can connect to it with the new wireless settings. If you mess up, you can reset the router to factory defaults by inserting a paperclip or pin in the small hole next to the larger USB jack on top of the unit. Hold it down until you see the router reboot.