Tar is most often used to seal a surface such as wood or concrete. A big problem in removing tar from concrete is that cement is very porous. It allows the tar to infiltrate its surface. Tar is also very sticky, which means it can't simply be scraped or wiped up. Try using some simple methods to remove the tar from your concrete floor, but be aware you may have to complete the task with a chemical product specifically designed to remove tar.
Scrape off as much tar as you can with a floor scraper.
Remove as much tar as you can with a power washer or sandblaster, if it's practicable where your floor is located.
Scrub the tar from cement with water and a scouring pad. Be aware this method will require much time and elbow grease.
Try removing the tar with a nylon scrub brush and mineral spirits.
Remove the tar from the floor with a commercial tar-removing product. (Examples of these are listed in Resources). Tar-removing products are available at hardware and home improvement stores.