Some cats do not like being picked up and will not allow it ever. It may be that they had a bad experience early in their lives (someone picked them up and did not support them or did something bad to them), or it may be that they are just uncomfortable not having solid ground under their paws. So, first, accept that you may never be able to pick up your cat at will.
Also, keep in mind that if you just recently adopted her, she may not know you well enough to trust you yet, and she may naturally allow it once she trusts you more. In my experience, it generally takes 6-18 months for an adult cat to settle into a new home.
That said, sometimes you can ease into it.
First, find some kind of suitable reward that your cat loves. For some cats that's a specific treat, for other cats petting and affection will work. Sometimes, it's worthwhile to establish a clicker training program.
Once you have a good reward system established, then just take it slowly step by step and reward your cat at every step.
If putting your hands in position to pick her up spooks her, try putting one hand in position. If she allows that, then give her the reward. Switch hands until she's comfortable with either hand, then try both hands (again, rewarding her each time). Once she's comfortable with both hands, don't pick her up, just lift a small amount of weight off her paws and reward her for that. The goal is to take tiny, incremental steps that she's comfortable with and give her lots of praise and rewards.
Each training session should be short (10-15 minutes). This is a marathon, not a sprint.
Once you're able to pick her up, keep your hands soft and don't restrain her. If she wants to leave, let her. You don't want to wrestle with a cat to hold onto her, you want her to trust you enough to want to hang out with you. If she knows she can leave at any time, she will gradually learn to trust you more and not want to leave immediately.