creating a custom registration form

[JornBart]

I want to organize sales events on my website: for a specific amount of time (let's say 2 weeks) brand x will be put in the spotlights. If we find (for example) 10 customers who are interested in buying brand X, we will organize a groups sale. Customers who are interested in purchasing items of this brand, have to register themselves via a registrationform.

 

I want to know how to go about:

* how do I create a custom registration form?

* how do I store this data in the backend?

* can I make a field in the form mandatory?

 

I want to be able to write all the data I get from my customers away in a database so I can easilyUAE out when the deal goes through or not.