Freight only goes to commercial buildings. The storage buildings only store it or move it to other cities, but if you don't have enough commercial to use it that storage will just fill up and sit there, not solving the problem. You can't export freight to the global market.
You either need more commercial, or you need to figure out why the freight isn't getting to said commercial.
To clarify: Industrial buildings need to make a certain amount of money each day or they will become abandoned. Each industrial building makes money each time it sells a shipment.
There are two ways to sell shipments: 1) Sell them to your local commercial buildings 2) Sell them globally via trucks, Sea Port, Train Station, or Airport
It doesn't matter which method you choose, because as long as you do one of them your Industrial buildings will make money off that shipment. If freight just sits around in storage, the industry will not make any money because the freight is just sitting there waiting for a buyer.
It sounds like the OP might have a lack of Commercial buildings, so he should probably zone for more Commercial or go for the second option. If it's a problem with delivering freight from Industrial to Commercial, then look into clearing up traffic on the road.