Sharon, watch the segment of TOH where they put one in somewhere like Arizona or New Mexico. This was a tough concrete job and it not only took a great amount of experience feeling what the concrete was doing but also having a couple of experienced guys on hand for finishing when it was the exact time to do it. There are some jobs that require expensive specialty tools and some jobs that require a great amount of art and experience. Both are best left to the pro's--on a cost if you mess it up basis.
How much experience do you have color matching wet batches of concrete? Very subtle changes in wet color make a huge difference in dry color. Do you know how to build really strong bases? Work with rebar? Have a feel for when the concrete is just barely workable on the top and yet it is still firm enough on the sides under the forms that it all will not go on the floor if you remove the forms? If you can answer "yes" to those, why are you asking here?