roof shingle repair after moving satt. dish mounting pole

Hello, Today I moved my satt. dish. The trees in my front yard had grown too large and were blocking the signals. I moved it from the top of the garage to a higher level on the main part of the house. Went from getting signals of about 50% to 60% to over 100%. Problem is the roof is about 4 yrs. old and the place I removed it from now has 4 holes. I did fill them with a silicon product that will stop any leakage through the roof but it is unsightly. I do have some left over shingles that the original roofer left me. I want to cut out(?) the shingles where the holes are and replace them with the left over shingles I have. How do I do this. Thanks for any info. Dan.