You have two outputs S and Cout so you need to construct a k-map for each of those.
S = f(A,B,Cin)
Cout = g(A, B, Cin)
Our goal is to derive simplified boolean expressions for both the functions f and g. K-maps are quite intuitive once you get the hang of them so I would recommend looking up some examples. Here is a rough idea of how to proceed:
1) label each axis of the table with at most 2 bits and write a separate column/row for each different combination (remember to use gray code).
2) fill in each cell with the corresponding output
3) circle each set of adjacent 1's and derive the boolean expression. This can be found by looking at the at the header and including only the bits that change in the expression.
After you have derived the simplified expressions, constructing the actual circuit can be done directly from the expression.