how to store digital sing pad and fingerprint value in c# and how to get that value

There are several accepted patterns in the Software Development Life Cycle. The classic 5-tier waterfall does still see use, but I prefer a 4-point Spiral, so we'll live there in my answer. Yes, I know there are many, many, many other architectural patterns, but we're reducing here.

Iteration 1:

1. Analysis. Identify an end goal for the software and get a good sense of the client requirements. You seem to have a good, general starting point, and this appears to be where you are.

2. Design. This is the phase where you develop the model which you will use to address the requirements identified in Analysis. Many software engineers like to use UML for this step, but I personally prefer an arcane combination of psudo-code and doodling(I think well on paper). You should do this before asking any code-specific questions, as you should identify what languages you'll be using in this phase.

3. Implementation. This is where you write code that implements the model that you designed in Design, using the language that you identified as the best fit. Otherwise known as "where the rubber meets the road."

4. Testing. Make sure that the code implementation matches up against the model, and ultimately against customer requirements.

Iteration 2:

5. Analysis: Now that we've completed one iteration, we can revisit requirements and decide if other requirements will need to be met, or if any requirements are different than we initially thought. This is perhaps the MOST crucial step in the entire SDLC, because it is our chance to throw out pre-conceived notions and properly identify the value that our software will bring. If your requirements haven't changed at all, you're probably doing it wrong.

6. Design: Decide what changes need to be made to the model and design them. Don't throw out structures just to do it. This is probably the HARDEST step, because it becomes easy to get wrapped around the axle and start micro-optimizing.

7. Implementation: This is basically the same. If you don't comment your code liberally and ignore all naming conventions, it becomes pretty common to go back and say "WTF did I do here."

8. Testing: You should be refined enough to move out of pure internal testing and push to Alpha version.

AND SO ON...

This isn't meant to be a snarky answer, just to illustrate where you are and what you should really be focusing on at any given moment in development. Your question was vague enough that I felt it was warranted.