Where do you sell goods?

[President Greevil]

I have wheat in my silos but I don't know how to sell it ;_;

[Maiteria]

http://guides.gamepressure.com/farmingsimulator2015/guide.asp?ID=27291

Pressing I, and navigating right, you'll see the places you can sell, also note the right arrow there, as there's several places to sell at.

Then look at your map, to find the proper place.

[President Greevil]

I can't find it, where exactly am I supposed to look and how do I know who pays the most?
EDIT I found it but it doesn't say which silo pays the most.Also why are some silos yellow while others are green and white?

[Maiteria]

Yellow is here you unload grain for example.
Green is where you can sell grass.
White is for random things like wool pallets, eggs, etc.

It does say what pays most - look at the numbers, when you press I, and navigate to the list of grain you have stored, it'll have all the various places you can sell, showing the price per ton (1 ton is 1000 liters, in this game)