What are the physical sexual arousal changes for females?

Hi,

Sorry for the silly questions ladies i'm 21 years old. Males (me) get erections as our sexual arousal i'm curious to know how ladies get sexually aroused? I'm a virgin and know NOTHING about sex, foreplay, and in general female sexual changes. I personally feel I have let myself down by not knowing females well enough as well as not knowing how to prevent pregnancy, STI etc. I learnt all the terms with sexual health but not all the body parts, arousal, etc.

What are turn on for ladies to be aroused like guys just look at ladies and go yeah but how does it work with ladies?

For general education, read Go Ask Alice!
Info for Teens - Planned Parenthood (technically, you are not a teen anymore, but since you have gaps in education, that website would be appropriate for you).

Women are in general more complex and the signs of arousals are more complex:
Clinical Fact Sheets: Female Sexual Response

Good luck with the practical implementation!

I'm not a lady but I have a little less clinical answer. There isn't any set in stone answer for your questions. Women vary greatly in what causes arousal. There are women who become aroused just by looking. With most women a lot more is required for attraction/arousal. It's more of an emotional and situational thing. Romantic, affection type things. You need to care and be interested in them as a person, not just as a potential sex partner and not as a sexual object.
You also seem to be curious about the signs of arousal if I'm interpreting your first question correctly. There are some obvious signs and some subtle signs and some signs that you would only see if the the two of you were engaged in foreplay.
Dilated pupils and a certain softness about the eyes. Posture and body language are good cues that a woman is interested. If you've already determined that a woman is receptive to you and you've moved on to foreplay there are more obvious signs. Breathing pattern will change. Many women will have a blush, especially around the genital area and the breasts/chest area. The nipples will become harder and erect. As arousal intensifies the vagina will produce lubricant fluids causing wetness and will begin to open somewhat like a flower blooming. I don't think we are allowed to go into any anatomical terms much here.