What can I do with basil, mint and lavender leaves, to make something for my cold and stuffy nose?

Lavender is ok. Lavender is a great anti infective, but if you're stuffy try eucalyptus. Boil some water (distilled preferably) and add in 1-2 drops of eucalytus, then place your face near (not directly over the hot water) with a towel over your shoulders...Essentially you're giving yourself a steam...You can use lavender this way as well.