Solution:
You need to buy a SSL certificate from a company like Verizon or InstantSSL. Then, you will need a web host who has Open SSL or another software for processing SSL certifcates installed.
When you purchase a certificate from Verizon/Instant SSL, they will give you some encrypted code using which you could configure your Open SSL software, and then having https:// urls will work.
This isn’t something you can do using plain php.