The tremserver.bat file should be included along with the other files in
this zip file. However, if you still have problems unzipping it or the .zip is somehow corrupted, you can easily create your own.
A .bat, or batch, file is simply a collection of commands that are executed when the file is run. To create the tremserver.dat (which is, by the way, not necessary - it simply automates the setting of variables that tremded uses to determine how exactly the server is set up. You can also set these manually at the command line) open up Notepad, add:
tremded.exe +set dedicated 2 +exec server.cfg +set net_port 32123
and save with the .bat file extension. In some cases, Notepad may automatically append the tremserver.bat file with .txt, which can be avoided by A)Wrapping the file name at save time in double quotation marks, or B) Changing the file preferences to show known file extensions.
Now, simply add tremserver.bat to the same directory where tremded.exe is and, assuming you followed the rest of Foobar's (excellent) guide correctly, run tremserver.bat and your server should start up.