The main web pages have information on how you can download FreeBSD. If you are having trouble, you might try a different mirror; if that doesn't work for you, your best choice is to try the freebsd-questions@ mailing list.
If you are confused about which version of FreeBSD to download, there is a section in the FAQ explaining the difference between the -STABLE and -CURRENT branches; there is another article called Choosing the FreeBSD version that is right for you which is unfortunately fairly out of date.