Please don't dunk your kitty! That will just scare her so bad and it is not necessary. I have to bathe ferals every so often and over the years, I found a really good system that works well, and leaves very little marks on the bather and no trauma on the cat.
First take some dry clean towels and start cycling them in the dryer to get them toasty warm.
Clip kitty's claws, just the tip, do not cut the quick.
Take a deep round bucket and make sure it is clean.
Use only pet shampoo not human products but if you don't have pet shampoo a few drops of DAWN liquid detergent will work.
Put the bucket in your bathtub, take an old towel and place it in the bathtub as well.
Set the bucket in the tub or shower, and put water in it only enough to cover the cat's back end. Don't fill it up or even put water in it halfway.
Bring the kitten to the bathroom, shut the door- have the towels ready from your dryer. If you have helpers have them bring you the towels after the kitty has had the bath.
Place the kitty in the bucket, the kitty will stand up and grip the sides of the bucket, that is fine, let her, and just restrain her gently with one hand. With the other scoop the water over her, get her nice and wet but not her head or ears, then soap her down. Place her on the towel in the tub, quickly dump the bucket, put more water inside of it and put kitty back in the bucket, rinse her off then towel dry her.
I usually use two buckets, it is quicker, and the buckets help retain the heat of the water. You do not want to use really hot water or really cool water either.
Snuggle with your kitty wrapped in warm towels until she is dry, then release, or if she refuses to snuggle, briskly rub her dry with the warmed towels.