Programming registers

Hi programmers!

I want some help in programming registers.
My PLC is Siemens S7-200

I have 2 digital inputs.
When both are triggered, register will be filled with zeros(000)
When input 1 is triggered, the register will loop binary like this.

1´st 001
2´nd 010
3´rd 011
4´th 100
5´th 101
6´th 110
7´th 111 and then back to 1(001)

The result could be shown as MW0

Hope someone can help me.

Thank you

looks like homework to me. think about counters and how integers are displayed as boolean