Sharepoint 2010 Microsoft SharePoint Foundation User Code Service

Overview

This service runs code deployed as part of a sandboxed solution in a remote, rights-restricted process and measures the server resources used during execution against a site collection-scoped, daily quota.

How to do 

1.     Build webpart solution as sanbox solution then package it to .WSP file 

2.     Go to Site Collection >> Site Actions >> Site Settings >> Click to Solutions >> Upload wsp file to solution 

3.     Start the service “Microsoft SharePoint Foundation User Code Service”

4.     Active WSP file

5.     Stop the service “Microsoft SharePoint Foundation User Code Service”

6.     You can’t active WSP file