i have a jpg file and i would like to paste it in the header. but in the style settings
you can only add an url address and i did not found the location of the
header in the php source.
How can i add my jpg file which is on my computer? (I do not want to upload it)
OK, this is an issue in its own right. Logos belong in the theme, therefore the CSS needs to be adjusted to accept your logo. It is not as straight forward as it used to be, damnit.. For this to work you need to understand how Themes work... so start with the Themes documentation and take it from there...