First time everything..nervous and advice

hi! i have never been with almost anyone in my life physically. i’m pretty sure me and the girl i reallllyyy like are gonna get physical soon when all we’ve done really is lightly kiss. Im so so nervous about getting physical for many reasons, but the number one reason being how does that even start? Like Im so nervous that it’s gonna be awkward from the jump. everyone says “it just happens! one thing leads to another!” and i can’t even imagine that being the case, as we are both shy girlies lol. how does that even begin to happen?