The code tab will not pop up for me

On the home page there should be an "Edit Profile" button next to your profile picture. Once there you can place all of your code including CSS and HTML into the "About Me" section. If your issue is nothing is appearing when you're in the edit profile section then the most I could recommend is trying it on another browser.

Let me know if this helps or not, if you're still having troubles let me know and I'll try to give a more accurate response :)