u/Confident-Yak-1275

I didn't realize there were sooo many vitamin c products/ formulas out there. I googled it and I'm more confused than ever. I want to add it to my skin care routine, but don't even know where to start. I use Tret .05 and azelaic acid. My biggest concerns are lightening my sun damage. My skin isn't really sensitive but is prone to dryness. What type of vitamin C is best? I can deal with hot dog smell, but now I read some are fishy ( yuck).