You start small! Small parcels of time where you leave her alone, so she will come to understand and trust that you will come back. Then gradually increase to more and more time. You will also have to decide on whether to give her free run of the house during that time, or create a puppy den like a small room (set up with all she needs), or if she needs to be crated for safety for herself and your belongings.
Leaving the TV on, or the radio can help make her feel less alone. Getting someone else to come in and 'check on her/let her outside/playtime/walk' will be important for the days where she is left alone for longer duration, especially if she is crated!
If she is not crate trained, then you will need to get on that before you leave her in the crate. You can train a dog to love her crate by luring her in with a treat but leaving the crate door open. Once she feels confident in the crate you can close the door while she chews on her treat and let her out right away when she is finished. Catch her before she panics or whines, so the experience remains positive. Once that goes well, then you can give her a treat in the crate which takes a bit longer to finish, with the door closed...you can leave the crate available to her as a cave to retreat to whenever she wants. Then, when you crate her for when you need to, you can give her a Kong with frozen food inside to keep her busy for a while.
My dog loves to sleep in his crate and goes in it all on his own. He pretty much crate trained himself.
We have another dog to keep him company which is great when we have to leave them alone in the house. Perhaps you could consider getting a second dog, haha?