How can I assign these valuables concerning places as correctly ?

[Halid Faith]

I have a file called A which contains variable values as below;
file1, abc12
foot1, cba11
boby, def123
...

Also I have another file called B which contains partly valuable values as following;
begin
Server valuable1
Client valuable2
end

I have to assign the first column valuables in A to valuable1 in B and assign second column valuable1 in A to valuable2 in B.
Finally I should see as following in a file called C
Server file1
Client abc12

Server foot1
Client cba11

Server boby 
Client def123

How can I do that ? Could you give me a script ?
Thanks