If you are behind a proxy you will have to set the proxy before using svn.
The procedure for the same goes as follows :
1. Open "servers" file located in ".subversion" directory in your home directory.
2. You will find following lines of code located in the file
# http-proxy-exceptions = *.exception.com, www.internal-site.org
# http-proxy-host = defaultproxy.whatever.com
# http-proxy-port = 7000
# http-proxy-username = defaultusername
# http-proxy-password = defaultpassword
Set the appropriate values and remove the '#' from the beginning. Make sure you don't leave any whitespaces at the front of the lines being edited.
After editing the code will look like
http-proxy-exceptions = *.exception.com, www.internal-site.org
http-proxy-host = defaultproxy.whatever.com
http-proxy-port = 7000
http-proxy-username = username
http-proxy-password = password
3. Save the file and exit.
You are now ready to use svn.