Really? , is that ssfe? :O.
Thank you for your advice.
Could you pls provide me the youtube link?
You have lube that kills sperm, so you should also use that with the condom.
By 17 and legal, do you mean it is legal where you live to have sex with someone? And, of course, by that standard, is your girlfriend "legal" also?
For what it is worth, when I was 19, I had a long-term boyfriend (2 years) who was intact. I believe he just put on the condom the usual way. Pinch the top as you put it on to leave a reservoir to catch the semen, and roll it down. Some of the agencies have good UTube videos showing how to use one. (I think Planned Parenthood does.) Practice on a banana so you can be sure not to put it on upside-down in the heat of the moment; that gets pre-ejaculate on the condom and also means it won't unroll.
Please do point out to your girlfriend that while condom use is fine, being on the pill or an IUD and also using condoms is really the only way to be safe, from both pregnancy and disease.