Urgent -> Creating Digital Signature in Adobe form

Hi, i was wondering how do i create digital signature in Adobe form. Can anyone help by telling steps to create digital signature? Or is there any information/tutorials i can learn from? Thx.

I have read

http://help.sap.com/saphelp_nw04s/helpdata/en/40/8a0b37e44d7c2fe10000009b38f889/frameset.htm

but it helps little.