Firstly you must access your router configuration page. To do this first try the 2 links below if these don’t work follow the 3rd link to find out the IP address of your router.
http://router.spiders-design.co.uk
http://router2.spiders-design.co.uk
http://compnetworking.about.com/od/workingwithipaddresses/f/getrouteripaddr.htm
You then need to find out how to change the DNS servers (have a look around – should be in broadband settings or equivalent) if you can’t find it then google change dns dervers followed by the make and model of your router.
To change these settings you usually have to login to your router. To find out your routers default password google router make and model followed by default password.
Then change primary DNS server to 8.8.8.8 and the secondary to 8.8.4.4 this will speed up your day to day browsing but not downloads. For information as to why this speeds it up read on.
Every time your browser visits a new site google.com or yahoo.com it has to Ping a DNS server to find out the physical IP address of the server that the site is being hosted on by using google’s DNS servers you speed up this service (because google is awesomely quick)
this wouldn’t however speed up downloads as the ping has to be done only once per site.