Hello and welcome to YT!!
There are a lot of different ideas on crate training, so I will share what has worked for us. When we found our little one, she was probably just shy of 4 months old and we decided to crate train her. We used a small crate that she could stand up in and turn around but that was about it. The theory is that they will not want to potty where they sleep.
We started by having really yummy treats that we would lure her to the crate with and then toss them in the back of the crate making a noise and them let her go in to get it. Leave he door open during the day and do this routine often. Have something nice for her to lay on, a special toy that only stays in the crate and yummy treats to reward her for going in. We began saying "go to bed", since that was the command our other dog went into his crate by. You don't have to shut the door everytime, but ideally she will relate the noise of the treat, going in and the command and put it all together.
Having her stay in there through the night begins with having her realize that her crate is her safe place and not a sad place. Now, what we did was get her used to the crate and then we would put her in it, by using the treats, and let her stay in there for small bits of time, longer periods as we went. Sometimes she would whine but she learned it was okay and that we were going to come back.
My personal thought is that they are kinda like kids learning to sleep by themselves. Sometimes they cry, but eventually they are fine. Of course, you don't want to just crate her and leave her for long periods of time if you can avoid it, but 9 times out of 10, they should be fine.
I hope this helps. Just be patient and love on her and getting her to know her crate as a safe place, her own "den" and she will be happy in the long run. Best of luck!!!
