Welcome to BleepingComputer!
The blogspot you use probably uses ads to provide income for its owner. I have a website on Geocities and they do the same thing when someone opens my page. They have to pay for their services so they give you the space free and let the ad guys pay for it - giving them the rights to advertise anytime anyone uses their page.
If I understand right, you don't have any other "ad" issues except for this so this sounds like the case.
If I misunderstood, just tell me...
"In a world where you can be anything, be yourself." ~ unknown
"Fall in love with someone who deserves your heart. Not someone who plays with it. – Will Smith