Immediately after building the Trader's Tent, you can upgrade it to level 2. 
To do this, open the Trader's Tent window and go to the "Upgrade" tab. 

To upgrade the Trader's Tent to level 2, you will need the following items: 
- 3 work tools (Cargo Port)
- 1 traveler's map (Trader's Tent)
- 10 saws (Colonial House, Upgraded Colonial House)
- 8 scotch tapes (Auto Repair Shop)
- 6 screws (Subway Station, Upgraded Subway Station, Central Station, Eastern Station)