EACCES, mkdir '/home/webgis/Documents/MapBox/project/OSMBright/layers'

I have installed POSTGIS and import OSM data before installing osm-bright.I follow the process but when I use tilemill ,see this
EACCES, mkdir '/home/webgis/Documents/MapBox/project/OSMBright/layers'
and no picture in project of osm-bright
this mean that I need add layers by myself??or any other problem? I need help~

Start with the reported TileMill error and the expected contents of /home/webgis/Documents/MapBox/project/OSMBright/layers. Check the repository setup instructions and determine whether TileMill should create this directory or whether the failure is an environment permission problem. Done means the project loads without the EACCES error and the expected layers or setup guidance are available.

Written by the indexing model from the issue text.