Advice on planning a text based browser game in PHP

Hi,

I am interested in creating a text based browser game. I am currently familiar with HTML, CSS, PHP, MySQL & a small bit of javascript. Would it be possible to create a large scale browser game with just these technologies? It should be noted that I am relatively new to programming/web development. (I have done 1 year in college and prior to that had no experience, I mostly do little projects in my own time.)

I have a great idea for a game which I think would be very popular, however I don't know if someone of my skill level could pull it off.

Anyway to get to the point:

1) Is it possible with the technologies I already know?
2) Can someone of my skill level pull something large scale off by learning the hard bits as they go?
3) Where do I start?

Let me elaborate a small bit on no. 3, how would I plan a large text based game? Obviously I want to start working on it ASAP but
I feel it needs to be planned perfectly for me to have a chance of being successful.


PS: Is it better to design web pages or program the scripts first?
I typically design web pages and then "fill in" the functionality as I go.


Thanks for reading & I'd appreciate any advice.


Thank You.