There are two ways to install Allegro:
*Note: #1 is easier, #2 is for if #1 doesn't work
1. Open up Dev-C++ and go to Tools>Check for Updates/Packages
Go the "Select devpack server" dropdown menu and select devpacks.org, and click "Check for updates"
If you get an error message like below, you will need to go #2. If it downloads the package list, you will be fine.
Next, go to the "groups" dropdown menu, and select Allegro.
Find and select Allegro 4.2.2, and download it.
2. If the Dev-C++ package installer doesn't work, use these steps.
Here is an external link to Allegro.(sourceforge)
Allegro download in Chrome Browser
Allegro downloading using Save As
Double click the file, and the installer should load.
If not, right click on the file, and go to "Open With", and browse to your Dev-C++ folder, and open with packman.exe
Using both methods, a install window like this(below) will pop up. Go ahead and install it, it only takes a few seconds.
Congratulations! You can now use Allegro game engine on your computer! Head over to the next tutorial to get started programming in Allegro