I'm a level 28 Night Elf and am trying to buy a mount and Riding training. How can I raise gold to afford this, and where can I buy the appropriate mount and Riding?
At that level the best way to get gold is to choose Mining and Herbalism as your two Professions, then do loops of areas mining and herbing, and auctioning the results. You can get sufficient gold quite quickly.
Having said that, these days levelling should give you more than enough gold to provide for your needs. Riding in particular should cost 4g for the basic skill and 1g for the mount as required at level 20. At level 40 you can get a slightly faster ground mount for 50g for the skill and 10g for the mount, but that shouldn't be a concern as yet.
To get the Riding and mount versions you can use, you can visit Darlene Stokx in Stormwind to purchase Apprentice Riding. You then need to visit Katie Stokx (next to Darlene) to buy a mount of your choice that you can now ride for 1g.