I don't want to rain on your parade but you don't just "pick up" PHP and MySQL to the extent where you are capable of delivering this kind of thing.
PHP is one of the easier languages to pick up, but MySQL is arguably one of the least friendly Database Management Systems to use. Products like phpMyAdmin give it a more user friendly interface, but this is only half the battle.
Database design is critical to the overall success of any project and the larger and/or more complex the project, the more important it is to have a very, very good handle on database design. Get things wrong at this stage and it doesn't matter how clever you become with PHP - the whole thing will fall over.
You seem to be talkng about a software engineering project and if it is of any real size you'd normally expect to be working as part of a small development team. It's very unusual to consider producing something of considerable size on your own, especially if you have no formal software engineering or web programming training.
I could suggest some resources for you to start with but if you've already agreed to take this job on you could find yourself in real trouble. I'm sorry if this sounds doom and gloom but I can think of no easy shortcut to get someone up to speed in any of the web dynamic languages and database design is a serious learning curve all on its own.
If you must learn one of the web languages then PHP is one of the easiest but .NET also has a huge amount to offer. It can interact with some very useful data sources and is probably as easy, or at least, no more difficult to learn than PHP. You would need different hosting though.
I wish you every success but this will be no walk in the park. If you haven't agreed to take it on I stongly suggest that you don't.
Post again if you want some links to get you up and running.