Internet Explorer in all versions is a dangerous browser. It has many deficiencies and security vulnerabilities that make it unsafe.
You should instead use a current version of Chrome or
Firefox if you're using windows or Safari for the Mac.
This site will not function properly in Internet Explorer. Emails will not be sent, downloads will not function, assignments will not be
submitted...
How to Install Ruby in OSX
Step 1: How to Install Ruby in OSX
Install XCode
Go to the Mac App Store and download XCode. It will take a while to download because at the time of this writing it is about 3.5 GB.
Once it's downloaded, install it.
When XCode is installed, start it up and go to the XCode menu, select preferences, and then choose downloads. There you'll see an option to download the command line tools. Download those tools and then when it's complete quit out of XCode.