why do i still have bullets by my pictures.Also my h1 header isn't being centered and my margins aren't working.

It's hard to say without being able to see your code!

To remove the bullets you need to use

#the-id-of-the-ul-element{
  list-style: none
}

also bear in mind that you could just target the ul, though this might not be advisabe if you had numerous ul's on your site (which you normally do!) and wanted to keep some as bulleted lists.

ul's also always have a margin and padding so you probably need to reset this with

#the-id-of-the-ul-element{
  list-style: none
  padding: 0;
  margin: 0;
}

Hope this helps, try editing the question with the code you have written.

you need to put it between (3 x the backwards apostrophe, next to left shift on mac, just below esc on windows keyboard) then the name of the language you're writing e.g. css then close it with another 3 backwards apostrophes. There needs to be a clear line between the opening and closing Check out the markdown cheatsheet linked near the bottom of the page.