Tried entering new header widget to my Theme PHP and crashed my site

I tried adding a header widget to my website so i could add the text code for an ad placement to my site and have completely crashed my site…

I am getting this when i try to go to my site:
Parse error: syntax error, unexpected ‘=’, expecting ‘)’ in /home/content/p3pnexwpnas02_data02/28/2812628/html/wp-content/themes/covertvideopress/functions.php on line 301

I am new at this and it is stressing me out…does anyone know what I can do to get it back up and to get an ad tag placed in my header for a 727×90 ad