how can I build a website with online price of Gold?

Can you elaborate what you mean by "Gold"? Do you want to pay for the service using gold instead of currency?

You'd make each user have a new field in the database with the name of money, then whenever they add money to their account and they pay you would need to get the amount of money of money they paid then convert that to gold (Whether you want it £10 = 1000gold or whatever) and add it to their money field in the database.

I mean to design a website with live universal price of gold.I need it for my colleague project.
can anybody help me?

I don't really understand what you want 100% but add me on skype (Yorkiebar14) and I'll help you on that. I don't have a mic atm but IM's will be faster and easier than this.

Find a current Resource online that maintains a Real-Time Gold price index, then you'll have to build a script that checks that resource, say every '5' minutes and updates your page. It's actually quite starightforward to do.

Web design requires Lots of skills so its better to cocern from professionals in designing field .

There is a website that offers html code for online prices of gold and other commodities.
CHeck it out here:
You should find all the gold html codes u need!