I am currently trying to dual boot my Acer Aspire V5-122P with Windows 8 and Arch Linux. Windows OS was already installed. I formatted my hard drive and finished a base installation of Arch Linux via USB. Note this laptop does NOT have a CD drive or Ethernet Port so I am only limited to USB and WiFi. During the base installation I had the Arch Linux OS on my flash drive and was able to connect to my WiFi via the wifi-menu command but now I can't. When I choose Arch at boot I login either as root or my created account user (Jon). I can't connect to WiFi. So finally my question, I have downloaded the latest Netctl package from another computer, saved it to a flash drive, plugged it into my Acer laptop, mounted the flash drive and extracted the package but I can't seem to figure out how to install it. I can't use sudo since I don't have it installed. Any and all help is much appreciated! Thanks.

archlinux has the best wiki ever, how did you even manage to install it without it?
it most definitely has the answer to your questions.
actually, i'm a bit surprised that you managed to install archlinux without installing netctl. wait, you're not using some outdated .iso?

@ondoho - I downloaded the latest .ISO for Arch and put it on a USB. Plugged the USB into my computer and ran an installation of it. I followed some tutorials found on Youtube, Google, and obviously Arch Wiki. During the installation when I had the Arch installation plugged into my computer I was able to connect to my WiFi perfectly. Once I rebooted in order to continue the installation process of setting up a GUI, I didn't have the Arch installation USB plugged into the computer, I was no longer able to connect to my WiFi using wifi-menu like I was able to earlier in the installation process.

@ondoho - I used other tutorials on the base installation process because there were some parts on the Arch Wiki that honestly kind of confused me and other tutorials helped clear some things up. Do you think it is best to retry the Arch installation from scratch again?

Shouldn't be necessary. Just boot from your installation medium again, set up the network, mount your actual Arch installation and chroot into it using the installers chroot-script, just like you have done at installation time, of course without the formatting and bootstrapping part.

Now just install any software you need and after a reboot you should be fine.

this:
https://wiki.archlinux.org/index.php/Beginners%27_Guide
followed it like a bible, and you'll be ok.