Want to try threesome but don’t know how

Hello, I don’t know how to explain this but I really want to do a 3some both ways

2 women and 1 men (my husband this case)

2 men 1 women (me)

My husband wants to do a 3some but only with another female which is okay but how do we find the other person.

We been married for 8 years but we are ready to do more!