Condoms will not protect you against STDs unless you use them consistently and correctly. To use a condom correctly:
Keep your penis away from your partner’s genital area until the condom is on because drops of semen can leak out before ejaculation.
With the lubricated side out, put the rolled-up condom over the tip of your erect penis and roll it all the way down toward the base. If you have not been circumcised, pull your foreskin back before putting on the condom
Leave about a half an inch of space at the top to catch the ejaculated semen and to reduce the chance that an overly stretched condom will break.
Withdraw your penis immediately after intercourse, holding the condom at the base to prevent it from slipping off as your erection subsides. Check the condom for signs of leakage
Throw the condom away after you use it; never reuse a condom
If you don’t have a condom, your partner may want to use a female condom, which is a soft, thin polyurethane sheath that fits inside the vagina and has a visible outer ring. A female condom doesn’t need protect against STDs as well as a male condom, but it’s better than no condom. It can be inserted up to 8 hours before sex and does not have to be removed immediately afterward.