Didn't you ask a similar question here the other day about getting into programming? Anyway, PHP isn't that hard to learn in general it's a scripting language it depends on how much time and effort you are willing to put into it, but you certainly can master it in a year. You'll need to learn about object orientated PHP too.
And again, if you don't enjoy programming this will only be like 10x more difficult for you. Sure you could possibly freelance with HTML, CSS and PHP but if you don't like doing it, there's no point your designs won't be as good, you won't be having fun and trust me it's a lot of work.
On a side note, PHP usually goes hand in hand with SQL and databases.
