You should read the sticky information on this stuff. But I'll lay it out simply.
It's all dependant on time frame. Some people take a meal of protein and carbs around an hour before for the "pre". That can be whole food proteins or casein and low to medium GI carbs, or a mixture of those things plus a little fast stuff.
Some people do a "shake" for their "pre". A shake doesn't just mean a weight gainer. It's whatever. So for immediately pre it is best to use fast absorbing stuff with juice or water, and not a huge amount. That way it wont be sitting in you stomach making you sick and crampy, robbing blood from you muscles and will be available within a timeframe that is useful.
Some people do both of those meals.
When I say post I mean IMMEDIATELY post. So technichally there is PWO and PPWO. post and post-post. Many people argue and argue that the PWO should be slow absorbing carbs and/or protein. It all comes down to paranoia over an inlulin spike. There is all the info you need in the sticky to explain why an insulin spike in this time period is a good thing.
Read up on it and decide what you want to do. I do a meal around an hour pre. Then a little fast absorbing stuff right before. For post it's ONLY fast absorbing in water for me and a follow up 45 minutes to an hour later.
This is all up to the individual. There is evidence as to why the way I've explained works best in an optimal situation. When someone says a certain way sucks you have to consider two things. 1. They've never tried another way and are just repeating things they've heard, or 2. The way they like works best for THEM owing to THEIR pysiology.
You have to experiment but the issue is mostly for pre-workout, which is very important. For post I think most people would benefit from the fast absorbing stuff in water and just dont do it out of shear paranoia about getting fat or become diabetic (whic is ridiculous).
Anything else you want to know about this is all on the board