peredur on "Help for amature!"

On your first question, your sidebar widgets have a background image:

.sidebar .widget {
  background: url("images/line-sidebar.png") repeat-x scroll center bottom transparent;
  margin: 0 0 15px;
  padding: 0 0 20px;
}

You need to add a new style rule (in a child theme if you are using a theme over which you do not have full control), like this:

.sidebar .widget {
  background: none;
}

If that's not simple enough, you need to wait until you can ask your developer to do it for you.

Cheers

PAE