C# Application for PDA-How to start

Question

I am thinking how to develop C# application for My PDA.
The full details of my PDA is

ITEM                           DESCRIPTION

CPU                            OMAP850

SPEED                        195MHz

RAM SIZE                  64MB

FLASH SIZE: 128MB

FLASH CHIP TYPE: M-Systems

DATA BUS:                16bits

STORAGE SIZE:         47.46MB

LCD:                            240*320

COLORS:                    65536

OS: Windows Mobile 5 or Greater

I am trying to develop a application which will run in my PDA.When a speacial type of sms come to PDA, my application will customise the sms,read some data from database related to the sms and will send back a msg(as sms) to the sms sender....

I am new in this type of application... so if someone give me a proper guidline that how can i start it and which type of tools(sdk,packages etc if needed) will be necessary for this type of allpication ,will be a great help for me.......

Please help me.....