Manual Clock

Hello.

How can I use a manual clock on my FPGA board?

I need that to my project.

I want to send data to my project every clock. I am using the swtichs 
like port in.. but the clock is very quickly. How can I control it?

Thx

PD: In VHDL.
PD2: My FPGA is a Nexys 2. 1200 FG320