I have a brick fire place with tile in front of it. I would like to put marble over it. The bricks have very course lines in them, but the flood tiles are smooth. Can I do it.

Thank you ,
me no carpenter

Yes, either remove the smooth tile or scuff it up with an abrasive wheel. Also, you can clean it and use an epoxy available at most tile/marble suppliers.
Take your time. Most jobs fail due to lack of time committed to prep. The pro takes the prep serious. The amateur hurries through the prep and then the job fails.
Good luck.
Mark

"I would like to put marble over it" all over what, the fireplace, the hearth or both? If you do mean to include the hearth please tell us what kind of tile is already there, likely it should be removed and not tiled over with marble.