I take it the anemone you have looks sort of like this then?
This is my sebae when I first got it on June 30th of this year. It was about the size of a toonie and it didn't want to stick it's foot to anything. I had to turn my MP pumps to minimum for 48hours and watch it while it tried to attach itsself. It's tentacles were not all that sticky either. It was a very sick and bleached anemone. Most of these type of anemones don't make it I'm afraid and they take a lot of care to bring them back to health.
To try to coax it to attach to the bottom I would reduce the flow in that area. Ensure there is a rock or perhaps something with a shallow bowl shape that this anemone can put it's foot into and will feel happy.
After a couple days with it's foot attached you can then try feeding it. 1-3 small mysis pieces at first or a krill depending on the size of it's mouth. NO SILVERSIDES, not even chopped up, they are being proven to be bad for anemones.
Feeding should be once every 2 days. This allows time for your tank to not get muckied up with anything that is uneaten.
It will also help if you have a good skimmer on your tank.
By the way, are the tentacles on your sebae small or are they longer?