(spoiler)do not read if you havent played lol!!!

I have gone to the place to take the boat to ( the fort) to get the platinum chip from benny and boone shot one of ceasers men and now i cant go back in save so i was wondering if someone could tell me the directions of walking there please help!!!!

You can still take the boat.
It's the raft at the end of the dock, though you're going into enemy territory now, so be prepared for an extremely hard fight.

You can't walk there, but you can still get there by interacting with the raft(treat it like a door). If Boone was the one who killed the Legionnaire then your rep shouldn't have taken too much of a dive. If its still above Shunned then they should attack you, as long as you leave Boone behind that is.

For future reference:
Boone+Legion=Firefight

You can still use the boat, and as long as your rep isn't shunned or worse you should be ok.
Otherwise, take Boone and lots of ammo

thank you but um lol i killed them all and do i just press on the boat?

Well thank you for your suggestions do i have to talk to the guy that died XD or press on the boat