Changing SSH/FTP Password, how?

Hello,

I am here the first time. I need to change the password for the SSH/FTP access.
It seems mine got hacked and I urgently need to change it, but I have no idea how to do this.

I have been in contact with So You Start support and they sent me some links.
But it is all so technical and I can not manage it.

I have been on this since this morning at 11:30am and I am at my wits end.

My last try was with Putty, but it will not let me in.
Is there anyone here that can give me advise please or may be able to tell me someone I can contact about this?

Many thanks in advance,
Michael