Ah, the oft-misunderstood semi-colon.
It really only has three functions in modern punctuation.
1. Joining two independent clauses.* This implies the two clauses are related and/or equal, or perhaps one restates the other.
The boys and I are on our own this weekend; we'll eat too many hotdogs and watch cartoons.
2. Use semi-colons between items in a list that already involve commas.
I have lived in Clay Center, Kansas; Manhattan, Kansas; and Lawrence, Kansas.
3. Making that funny smiley thing I use too often.
Make peace with the semi-colon. Please. I hear the rapture is coming this weekend, and I wouldn't want semi-colon hate on my head.
*independent clause is a fancy way of saying "sentence". An independent clause is a string of words which can stand on its own.