Cannot upload pictures

I just started a new photography blog and am trying to iron out kinks.I am using the seashore-10 theme
https://ceconn.com/saycheese

• After writing a post I wanted to upload pictures and got this error:
  The uploaded file could not be moved to /home/cecon46/public_html/saycheese/wp-content.
  Warning: Cannot modify header information – headers already sent by (output started at /home/cecon46/public_html/saycheese/wp-admin/admin-functions.php:1986) in /home/cecon46/public_html/saycheese/wp-includes/functions.php on line 1357
• This theme lets you change the header image – except it won’t let me. When I tried to upload the image, I got an error saying I can’t do it but didn’t say why.

What is this all about? Can someone help me?