It seems to be impossible to reblog your own post from the main tumblr account, but it isn’t…
To do it, you just need to write it like following to your browser:
It should look for example like this:
More tumblr tricks here…
Enable mobile theme On the Customize screen turn off the Use default mobile theme option under Advanced Options. 
Display avatar image Upload an image to the "Header Avatar" option, square images work best. 
Remove stash credit Remove the stash logo from your website by getting a Full License.
Change Logo Image Height Add Custom CSS under Advanced Options: .logo img { max-height:200px; }
More help & customization If you still need more check out our help section or the theme docs.