You need to find some basic information about your William Leslie, such as:
Date of Birth, Date of Death, (death certificates sometimes show place of birth, and usually date of birth), or place of birth, ans approximate date of birth, then you can search Scots Origins. If you went into Scots Origins with just a name such as William Leslie, you would probably get hundreds of hits, and never be able to sort to your ancestor. You might also search Ships' passenger lists for the year 1881, you might find some basic information. My William Leslies back to my great grandfather, never left Scotland.