How do I get my website up and running? please read on...?

I am currently in the process of setting up a part-time home business. I have my product, I have a domain name and a server host. I have my webpage layed out. eg, my homepage, sales page, thankyou page etc. but this is where I run into a wall. You might say that i'm a complete dummie when it comes to anything more than typing a website address. that being said my problem lies in setting everything up in such a way that I don't have to do anything once it is up and running. I need a way to accept subscribers, have my sales page connected with paypal, allow the download of my product from my thankyou page and most importantly be able to achive this without doing anything once it is set up. I need this to be almost completely automated due to work and lack of spare time. So my question is, Can you suggest any software that can do all of this, or some part of it? any helpful sites? or any tips that you can give me? anything would be greatly appreciated... thank you