It depends where you order the server, some have instant setup, which means that it will be ready instantly, and other have manual setup, which can take a longer.
When you rent a server from a hosting company, you can't just press samp-server.exe, since most hosting companies run linux.
Mostly, when you rent a server somewhere, they have a control panel, where you can start-stop-restart your server.
If you want to put files in one of the server folder, you can use FTP to connect to the host, and place (upload) your files in the directories you want.
For that, you can use a FTP client like Filezilla.
When you order at a host, they most likely send you an email with the details needed to connect to your control panel and FTP server.
The ordering happens (most of the time, if not allways) on the website of the host themselves, so go to the website of the host you want, and search for the order section.
If you need any info, just ask, there are enough people who will tell you what to do
