Hi Bratman,

I guess everybody's nervous - you stated your gender! It really doesn't matter, concreting is hard work for anybody. I'm no expert but you deserve a reply - perhaps somebody else can help us both out!!

Much depends on the climate in your neck of the woods but as a general guide, here are the basics:

First of all, I believe 3 or 4 inch thick concrete should suffice for your purpose.

1 Decide and mark out the exact size and location of the pad.
2 Dig out top soil or whatever to a depth of around 6 inches (hopefully you'll hit relatively firm ground)
3 Beg, borrow, steal or buy long enough lengths of say 1" x 6" new or used lumber.
4 Secure these around the perimeter the "hole". NOTE 12' is quite wide so consider putting in cross peices and divide the whole area into sections. A few nails and strategically placed pegs knocked into the ground to ensure the "form/shuttering" stays in place and straight when the concrete is poured. If you are game enough to tackle a job like this - your instincts will probably tell you when it is ok! Play around and adjust all the wood to the desired level - you can slope to a certain degree.
5 Fill the hole to depth of about 2" with gravel - I believe 1/2" or 3/4" will do.
6 Order your ready-mix concrete - tell the supplier the size and depth of the project and they will deliver the correct amount. Basically, if you imagine a cubic yard of concrete sliced into 4" thick pieces you will have 9 pieces 36"x36" 4" thick. Calculate the area of your pad and divide this by 9. eg If your pad is 12' x 15' this is obviously 20 square yards. You will need 2.25 cubic yards of concrete. NOTE Have another place ready to "dump" any extra - perhaps a step someplace!
7 When the concrete is delivered have available a straight piece of wood to stretch across the top of the "forms" to level the concrete AND a friend to help you with this!!
8 As the concrete is poured by the supplier, you and your friend will frantically spread it out with shovels til the all sections are full.
9 Rest the levelling piece of wood on top of the forms and go for it - using a "lumberjack" sawing motion working from one end to the other and level the concrete.
10 In your case, I would allow the concrete to set for an hour or so and then, using a brush/broom, sweep the surface to obtain a reasonable "brushed" finish.
11 If you are in a very hot climate, spray the concrete with water for a day or so to stop it drying out too quickly.

Please excuse the "math lesson" and somewhat vague instructions but it may stir a more qualified person into disclosing a more detailed method. But at least the above may be helpful in giving you a rough idea of what's involved.

Good luck. Alan

3" is not enought to hold a car. I think driveways are about 5" but not sure you will have to ck on that, it should also be renforced with rebar. It also has to have a proper base of sand and gravel, very important. This is alot of work. I would go to your local home depot or similar and pick up a book, also be aware that amout of concreat you can't mix yourself, even with a mixer. You have to get it trucked in.
I don't want to scare you but it is a big heavy, ugly, job.