Singlespeed & Fixed Gear - Single Speed help

I'm new to this forum and the world of single speeds. I know you guys probably get this all the time, but I need some basic single speed help. I'm converting my '73 Schwinn Varsity to a single speed. I have everything else worked out except the most essential part: the chainring + the cog. I understand they run in a system of teeth and that the lower you go in your number of teeth on the cog, the harder you push.

The gist:
I'm going to ride on almost 90% flat terrain; Lincoln, Nebraska.
I'm buying a Surly cog.
I counted the teeth on my original chainring still on my bike and it has 39 teeth. Does this mean it's a 39-tooth chainring? Stupid question? Probably. Please recommend good ratios for similar terrain or advise me to options with corresponding locations; i.e. ( 42/16 Chicago, Illinois etc)

If anyone could help out a single-speed novice, that would be awesome.

Thanks so much,

Max

http://rabbit.bareknucklebrigade.com/rabbit.applet.html

The Rabbit is going to answer all of your questions- If you're a relatively strong rider, I would say to go for something around 75-80 gear inches on the flat ground. When you get more used to the SS you can a bigger ratio, but I'd say thats close to what I'd want. A lot of people start around 70 gear inches. Also, if you have a road bike, practice riding on your usual turf in one gear and figure out what works for you. Then count the teeth on each of the cogs. Put it into the Rabbit and figure out your Gear Inches, and go from there! Good luck!

Thanks so much falcon!

Post some pictures if you get a chance. I'm kinda a fan of the varsity.

Will do Bala! I'm thinking it'll be finished in a month at most. I just have to wait for my mileage check from the state to pay for all of this. Then, it's all down to shipping. But once I get it all in, I will finish it within two days.

-max