The jpg  and the stp file you make go into your "viper Racing/Data" folder.
To create an stp file for your track to show in the game lobby,first
you make a tga file ,export it to this folder with the option 24 bit uncompressed.
Exact name of track is required.Example: Track29.tra means the tga will be Track29.tga
Right click on the tga2stp.bat file ,click edit ( opens with notepad ) then type your
track name where it says Track29.
Close it / save changes then double click it to convert your Track29.tga into an stp file.
Now the stp file must be modified using the hex editor.
Double click the stp file,open,choose Xvi32.exe < your hex editor.
When it opens the stp left click on the first digit,top line on the right side 
and keep clicking the delete key untill you have the "!" at the front of the line as shown in the tut image.
x out of that / save changes.
Now you can put the stp and jpg into your "Viper Racing/Data" folder.
Don't forget to zip all these files together; Track29.tra,Track29-readme.txt,Track29.stp and Track29.jpg and call it Track29.zip or Track29.rar ( for example ).
NOTE:
This stp file is different than the one in your "track2gamefiles" folder.