Check out web pages from from !GitHub at https://github.com/SasView/sasview.github.io.  This can be done with
 * Eclipse (or some other IDE)
 * GUI git (like tortoiseGit for example) - this will require having valid credentials.  In principle this is not required for check out but will make checking in much simpler. 
 * Command line git. For this type:
{{{
$ git clone https://github.com/SasView/sasview.github.io.git
}}}
If you already have the repo locally you just need to update the repo
{{{
$ git fetch origin
}}}

Once the changes are made they should be staged and committed.  If using the command line:
{{{
$ git commit -a -m 'commit comment'
}}} 


Finally, the commit will need to be pushed up to !GitHub from the local repo.  Again if using the command line
{{{
$ git push origin master
}}}

Once the !GitHub repo is updated, the website changes will automatically be live.

NOTE: the above command line makes a few assumptions about your setup.  If they do not work you should look into git documentation.