How do i teach my girlfriend to improve at sex.

I am 26M and have been dating my girlfriend, 22F, for about 2 months. Getting straight to the point. My girlfriend is bad at sex. Like she doesn’t even know how to give a handjob properly, when I’m flaccid she practically just tugs on my foreskin. This could contribute to the fact that she’s a virgin and im the first guy she’s gotten completely nude in front of. Same goes for blowjobs and everything else. I love this girl and i wanna improve our sex life. The problem is that if i were to show her how to do it correctly, between instructing her i kinda lose my erection and out of the mood. Currently our sex life is a mess. How can i make her better, or i don’t lose my erection between the time i show her how to do it properly? Is there a third option? I’m open to any suggestions to improve our sex life.