JillSinclairBelanger on Family Tree Circles

I'm trying to find my lineage back from Scotland. In 1965 my grandfather, Roy McKay Sinclair, went to the city of Wick, located in the northern part of the Orkney Islands, in Scotland. He said he was given the key to the city because so many people remembered his family history from that area. He was able to purchase the family clan material to bring back to me. I being his only granddaughter. I've since found out that it was the ancient colors of the Sinclair Hunting Tartan. My mother being the excellent seamstress that she was created a kilt for me. I still have it.
My question is how, or where, can I find the connection from my grandfather to the people in Scotland? My father was born in Winnipeg, Canada as was my grandfather Roy. Roy's dad, William Sinclair,was born 1845 in Scotland, I don't know what city. He married Whilhelmina Omand and her fathers name was John Omand. That is all the information I have. I am currently in the process of ordering Roy's birth certificate but don't know how that will go.

Any information will be greatly appreciated.