Click the Publish Site icon, where you need to create a profile to use for your new website.
For the new profile, choose remote, and enter the upload details for you webspace. (If you have an ISP, then you probably already have some webspace. If they don't provide any, you will have to find some free hosting or buy some). 1&1 do some good deals with a domain name thrown in. Free ones usually have advertising which can spoil your website.
NTL proved 55 Mbytes, Plusnet provide even more.
The new profile dialogue looks like this: click here
The details for the FTP host you will need to get from your ISP. For NTL it is upload.ntlworld.com.
Then you are advised to enter a directory so that you can publish more than one website to the same webspace, or store some pictures, etc. Your password will be given as part of the ISP registration process, you can change it later.
You don't need a domain, unless you want to be famous.
This is my website on my domain: click here
and this is the same website published to my ISP webspace as a backup (mirror) in case my domain server goes down: click here
Note the different addresses, but the sites are identical (almost). A domain address must be made to point to a webserver. Someone else did that for me, so I don't know how to do it. Cross that bridge when you come to it, if you decide you want a domain name. The benefit of a domain is that it can be something short and catchy like bbc.co.uk.