In ShipStation, it's really easy to connect your IMEX account to your ShipStation account.
Head to your Account Settings (the wrench icon in the upper right).
Next, select Shipping and then Carriers & Fulfillment from the sidebar on the left.
Once you do this, you'll need to click on Add a Provider Account.
Select the IMEX tile and choose Confirm.
Enter your provided Username and Password, then click Finish.
And thats it! You're now ready to start creating labels with your enabled IMEX services in ShipStation.