Hi Marry
This is good blog to start with
In terms of creating a process and form (Adobe based) there are tutorials in the SAP help -->
Tutorial: Create a Process - HR Administrative Services (PA-AS) - SAP Library
That said I think these were developed before HRASR_DT transaction - so it mentions the IMG nodes required to design a process - nevertheless the principle is the same
There are also new tutorials for FPM based forms in SAP Help
Hope this helps
Stuart