read xml in C#

How read one xml file and form another xml file using C#?

I have a xml file like,

<policydetails>
  <current>
     <no></no>
     <type></type>
</current>
<prior>
  <no></no>
  <type></type>
</prior>
</policydetails>

I need to read the above xml file (read nodes like policydetails, current) and using the node read another excel file get the value for spefic node,

say for eg, from xml read the node policydetails and get the value for policydetails from excel file.

Then I want to use both the tag name and value from excel and create another xml as below,

<policydetails>
  <current>
     <no>1</no>
     <type>A</type>
</current>
<prior>
  <no>2</no>
  <type>B</type>
</prior>
</policydetails>

I want to do this in C#, please help