
I'm assuming she's KC registered, has no endorsements on her registration, is between 2 and 5 years old and has passed all the breed-relevant tests for hereditary conditions. (Of course the stud would also have to meet the criteria, other than the age limits, too.) If not, the sensible thing would be forget about breeding from her.
Otherwise, contact her breeder who, if reputable, will advise you which bloodlines are likely to give you the best results - using the wrong stud can produce a heart-breakingly disastrous litter. Be warned - the most suitable stud is invariably over 100 miles away - but it's foolish to use the wrong one just because he's nearer.