The rules for solving this are exactly the same as a usual SuDoku puzzle.
When you have completed the puzzle, substitute the letters for numbers and solve the simple cypher.
Cache is hidden at the following coordinates:
S 17 (U-J)(R-A).(N+T)(D+K)(L-M)
E 25 (P-G)(B+F).(R-F)(C-K)(S-N)
You are looking for a small sized cache. If you want, you can use the geocheck link below to check the solution before you attempt to find the cache.

