These are standard methods to add a trademark symbol to any program on your computer. They are built-in into your operating system and available in every program you have: Word, Picasa, Visual Watermark and all others.
Mac
It is very easy to add a copyright symbol on Mac
Press Alt and 2 on your keyboard
Windows
Windows provide a much trickier way to type a trademark symbol to text fields. You should
Press Alt and 0, 1, 5, 3 on your keyboard
Yes, this is a four step key combination. You should hold the Alt key while pressing the 0 1 5 3 numbers. Here you can find a video showing how to press a similar combination that adds a copyright symbol: How to Type a Copyright © Symbol