Go to System > Configurations, and click the General tab in the left side menu under the General section. Expand the 2nd pane (Store Information) and fill out the fields shown below prior to submitting orders.
Warehouse Origin Address
ShipStream will not allow orders to be processed until the Warehouse Origin Address has been set for the specific warehouse originating the order.
Go to System > Configurations, scroll down to find the Shipping Settings in the left side menu under the Sales section.
Expand the 2nd pane (Origin Address) and fill out the warehouse address to set an origin for the orders.
Enable Shipping Carriers
While in System > Configurations, click the Shipping Methods tab in the left side menu under the Sales section. Expand the pane for the shipping carrier you wish to enable and select Yes in the "Enabled" drop down menu.