Run the tool from the command-line because there are also other options and many modding tools run from cmd, so learn to use it
Open the command-line by selecting Start->Run and type cmd.
This is the prototype of syntax you have to use:
ttarchext.exe -m 61 c:\PATH\FILE.ttarch2 c:\OUTPUT_FOLDER
You don't have to type the last two arguments, just drag'n'drop the file (and then the empty output folder you created) on the black command-line.
More info about the command-line:http://aluigi.altervista.org/about.htm#howuse
The Internet is full of plenty of information about cmd.exe and command-line, there is nothing really to learn, just some notions about the current directory, arguments and so on.