New house, new Cat5, confused by connector / wiring block
For a basic description check this page on wikipedia: http://en.wikipedia.org/wiki/110_block
For more detail on how to install one, take a look at this one as a start: http://cableorganizer.com/phone-data-connection-blocks/110-installation-instructions.htm
If you don’t already have one, you’ll need a punch-down tool. I would recommend one with a metal blade. Some kits will come with a small plastic one but they often don’t stand up to more than a couple uses.
Even though you don’t have more than 1 phone line, I’d suggest that you connect at least 2. You never know what you may need in the future (additional line for kids, home office, fax machine, etc).
Anyway, you would strip a short bit of the wire and it will go into a little slot-like terminal. You use the punch-down tool to press the wire into the slot. The wire should then be fairly firmly fastened.