I'm uncertain what you want to do. As you should know, a Waveform has an array representing values at equally-spaced time intervals, where the time is implicitly given by the t0 and dt parameters (see Get Waveform Components on the Waveform palette).
If you want X() to be Time, and Y() to be the array in the Waveform, then you can build X as an array [t0, t0+dt, t0 + 2*dt, ...] or, if the exact date/time are not important, as [0, dt, 2*dt, ...], and use the Y component of the Waveform for Y().
Your request makes no sense.
A classic waveform only includes Y values. X values are implicit because samples are 'equidistant'. Your X-values therefore compute by "sample number * delta t". Delta t is one meta information contained in the waveform datatype.
and detect the first and second peak is important[...]
What do you mean by that sentence?
What does the exponential fit in your attached VI?
Why don't you pass the Y-data from the waveform (hint: Get Waveform Components) to the peak detector VI?
with the exponential decay i want to find damping of he signal and with peaks i need to find time period
from oscilloscope and i have this waveorm wire i need to split it into x and y components
here is a littele progress from me i just need exponential decay and to detect selected peaks from waveform i get from oscilloscope
User Bob_Schor allready describes how to split Waveforms.
Maybe this Screenshot will help you to understand.
Is your question answered then?