If you want to download and save the contents of a certain page to file you could use the -O file
option:
wget "https://www.betfair.com/exchange/plus/tennis" -O tennis.txt
Please be aware that on some systems (CentOS and others) the order of parameters in the command line is important.
wget -O FILE URL
works.
wget URL -O FILE
does not work (at least on CentOS).
If you want to download a whole site using wget, you can do the following:
$ wget \
--recursive \
--no-clobber \
--page-requisites \
--html-extension \
--convert-links \
--restrict-file-names=windows \
--domains betfair.com \
--no-parent \
www.betfair.com/
INFO: If you would like to suppress tracing information you can use '-q'
For more information, see the wget man page:
$man wget