If you want to make a free site so you can have a forum or a personal website, here is a simple way to do it.
Before you start, you should know that in order to make a webpage, you need HTML knowledge. A good program is Dreamweaver or MS Frontpage (from the old versions of Office). In flash format, a good site that does the job, is Wix.
For start, you need to register a domain. A good site is this. Now, you need to find a good hosting to host your pages. The best free is 000webhost. It provides you with 2 databases, 1500 MB of space, 100 GB/month of data traffic (good enough for simple sites).
Note that sites that provide free hosting will give you a domain like mysite.freehost.com. It is best to create a free domain like www.name.cc to make it look better. However, this does not needed for your site to work, but is for "aesthetic" reasons mainly.
We are now ready to upload the files you have and get started. When you sign up, the site hosting gave you a username, password (basically what you have chosen) as well as access details of the database and the FTP Server (important).
Download the free program FileZilla, which will take care of uploading your files to the host's server. Run it, put the login details given to you by the company (for FTP server access, not for the site) and start uploading the files.
When the upload is complete, go to mysite.freehost.com/install.php (depending on the script) and start the installation. You should also enter the database access details here.
Your site is ready. Pay particular attention to content. If it's illegal or pornographic, they'll close it immediately. The same is if it contains links to illegal material. Also, do not upload pictures etc, because if your site has a lot of visitors, it will drawn you bandwidth.
If your site goes well, move to a better hosting.