You will need to learn HTML and CSS to make the page content and style it to how you want it, then you will need some server side (PHP or ASP) and some database (SQL or something) skills to make your membership side of things work.
This is not going to be as easy as you are thinking I think. To learn HTML and CSS to a good standard your looking at 6 months (at least) then to learn then another year at least to learn server side programming skills and database skills.
If you wanna learn HTML and CSS these couple of sites are exellent.
http://www.w3schools.com
http://www.htmldog.com
You could cheat and use Dreamweaver in design veiw to design your content and style of the site, though I would advise against it as all WYSIWYG editors write very poor code and you will not understand the code you need to edit in order to do the membership side of the site.
You could get a pre made system of some sort depending on your requirments but I would also advise against that to cos you wont know how to edit things or fix anything when it goes wrong.
So there is no short cuts to where you wanna be really.