Use a Professional
Your local veterenarian is likely familiar with the process and can apply freeze brands for a reasonable fee.
If you happen to be in East Texas, check out www.texasbrands.com their site also has some basic info and photographs of The Branding Process.
In North Central Texas you might want to check out www.lazyabranding.com they also have some images of The Branding Process.
Here is a link that lists several contacts to perform the freeze branding.
Do it yourself!
The information in this section will tell you all you need to know to apply attractive freeze brands to your own animals. Most of the information is contained in .pdf files published by various State Universities. When you purchase a custom cast freeze branding iron from Pittsburg Foundry, printed instructions describing the process will be included in the box with your branding head. Since the files are in .pdf format, they can be easily printed on standard paper if you want to get started now with a branding head you already have.
Links to instruction sheets from:
Texas A&M University
University of Nevada
Oklahoma State University
West Virginia University
Here is some online info from the University of Missouri if you are having trouble reading the .pdf files.