Your semi-truck lawyer will help you start an investigation into who was liable in the crash. If the truck driver themselves is liable and owns and operates their own vehicle, you’ll pursue their insurance company or sue them personally.
In most cases, the truck driver works for a company that owns a whole fleet of trucks and covers them all with a large insurance policy. So you’d arrange an insurance payout with the trucking insurance company.
In most cases the trucking insurance company would pay any settlement or judgment.  In some cases that company will be self-insured so the actual trucking company will pay out of pocket.  Either way if the case needs to go to litigation you would typically file suit against the truck driver and the trucking company to cover all of your bases.
It’s not always as simple as it sounds, though. Today, trucking insurance companies are trying to pay less and less to injured victims. You may discover that the insurance company will balk at paying, just like the trucking company and the trucker themselves. You’ll need an experienced semi-accident lawyer to hold the right party responsible for paying.