TOPIC:

I was playing on server 30 and I just got a train to get building materials, I give it to the city and it just stays at the station. the city never picks it up. How do I fix this?

You need an industry which accepts building materials. To find out which industry accepts it click factory icon, and pick up from menu "Industry chains". Then select cargo: "Building Materials". Now you see that building materials is accepted by Bulk Terminal, Hardware Store and Builders Yard. One of these must be in close range of your town. When you build a railway station near to the industry, make sure that the beginning of the station name matches name of your town (to be sure to deliver cargo to correct town).

Note: It is wise to claim the city which already has e.g. Builders Yard. Or: you can fund any of required industries, but - usually at the beginning of the game - you're short in money.

I hope it helps a bit.
Happy gaming!