how to use nest if statement in excel or better way?

i have column A1 to A10 and another column B1 to B10

In my Column C1 to C10 the value is from any One of A1-A10 ( that is customer enter)

If C1 = Any of A1-A10 ; Then D1 should pop up the Value of B1-B10 corrosponding

for example C1= A5 ; then D1= B5

for example C2= A2 ; then D2= B2

for example C3= A10 ; then D3= B10

.....

this is done in excel

please help thanks