As hard as it may look, making classifications for a single race doesn't require too much knowledge once you get around it
When I make one, I never start from scratch, thus I open an already made one and tweak the details. This is what you need to do:
1. Go in the main game folder -> XML -> Classifications
2. Open any of them with the notepad or using notepad++ which I, for one, wholeheartedly suggest (the ones named top are the classifications files of the wt races, the ones named t0, t1 and t2 are respectively the ones of hc, .1 and .2 races)
2a. However it's not really easy to understand when looking at notepad's layout so for the first times I'd suggest you to open it with Excel or with a free alternative like LibreOffice/OpenOffice's Calc. The reason why you can't just work on them with these programs is that Excel and its alternatives don't save the xml file with the same output format as the original file you are going to edit.
3. Then it's mostly easy to work on it. A quick example: if you want to increase the bonifications for a win in an intermediate sprint, look at the row where it says: source_in -> sprint, type_in -> time, source_out -> race, type_out -> time. Then there will be the ranks, if a rider gets 1st you can tweak his bonification to say -10 to -20. It's vital you put a - in front of the number, otherwise winning a sprint will make a rider's GC time worse.
4. Then save from notepad or notepad++ when you are done to xml format (make sure it's not txt, selecting "all files *.*" and changing the file extension) with the filename as divisionid(so top, t0, t1, t2)_raceconstant(the one you saved and added your stage with) so it could look like t1_abudhabi, where t1 is 2.1 division and abudhabi is Abu Dhabi Tour's constant
Really it's harder to explain than to work on it, so take a look at the xml file in excel and all will be much much clearer
Any question, I'm here to reply them since I obviously wasn't too exhaustive on this.
