Post Status: They mean just what they say:
Draft, you can write a post designate it "draft" and save it. At a later date call it up to either finish writing it or edit then save as draft or publish it.
"can i change a grope..." You misunderstand what the password of for. It is used to PW protect as post. A PW protected post/entry would only show the headline and a place to enter the PW. It's used to keep only those you desire access to certain entries/posts. EDIT In looking at your site I see you have a PW'd entry. As far as I know you would need to change the PW on each entry you place one on.
Trackback TB's are meant for a way to "further a discussion."
Example: You have a post (blog A) about apple pie. Your friend also has one (Blog B). To use TB place the TB url from Blog B in the TB section of your write page. (it's under the upload section) The TB url is normally located on the comment page of many themes. although some have the url on the index page.
There is a bit or courtesy involved using TB's It is considered good practice to place somewhere in the text of your post a link to Blog B's post that you TB'd to. That link is the permalink url. (i.e. the one that contains the title)
Example: ".... and that's my apple pie recipe. Betty also has a very good recipe at her site." Her site would be linked to her post permalink.
Keep in mind this generally the etiquette iinvolved. Some bloggers overlook it, but many will delete a TB comment on the blog it a permalink to their post isn't included in your post.