You're thinking of Balsamiq Mockups - or, if you're looking for one to mock up desktop applications (and aren't opposed to using software from the Evil Empre), Viso.
>> I am attempting to teach myself Rails and have also made a concerted effort to understand Ruby.
There's your problem number one - trying to use and excel at Rails without understanding Ruby means that even if you become a moderately proficient Rails user, you won't know what you're doing, and will be unable to process past something you have a cookbook answer for. You can drive a car without understanding how an engine works (and assume that when you press the pedal down, "magic happens" and you accelerate), but to become a great driver you have to understand what makes the car go, and how to react to and optimize your behaviors for that.
Ruby is a language that does more than Rails.
Rails is a framework that's written in Ruby.
Learn the language first; then you'll know what's actually happening with Rails and what those commands mean. Net result is that you'll be a better Rails user, and you'll be able to use Ruby for many other things and in novel ways.
Separately, learn about database normalization and design. For this, start with the mantra "down, not across" - your tables should be much longer than they are wide, even if this means multiple tables.