First off: Fill up your tub with water. You can use a bucket or a sink but I prefer my bathtub (make sure it's clean first though).
You're also going to need soap or detergent.
Dump the detergent into the water and put the bras into the water.
You're going to let the bras sit in water with soap for a couple of minutes and drain the water out. You can repeat this step as many times as you feel needed. I personally repeat this step twice. Then fill the container/tub/sink once again.
Put more detergent in and gently scrub your bras.
Let the bras sit once more.
Then gently squeeze the water out of the bras and drain the water.
Fill the tub one last time. This time with no soap.
Let the bras sit in the clean water in order to get the remainder of the soap out.
Drain the water.
Gently squeeze the remainder of the water out of the bras.
Clip the bras.
Lay flat to dry.
I personally recommend to take a day for this. The process is very lengthy. The bras take anywhere from 6-12 hours to dry. Happy washing!