Soil layer required with AGWA in arcmap!!

Hi,

I am trying to simulate rain on a topography. I followed the guide of AGWA2 and I got stuck at the step where it requires the soil layer in the parameter section. I downloaded soil maps and added it but it does not appear in the combo box for soil layer. I downloaded a soil database which I can select from soil database combo box. However, for the soil layer option I am completely stuck. I tried .lyr and .shp formats but they are not listed for selection.

Could anyone please advise? Is it possible to build our own soil layer maps to be used for this purpose? I urgently need your help.

Thanks & Regards

Faraaz