We've been potty training for... some time... my daughter thinks it's a hoot. She loves sitting on the loo, wiping, flushing - but doesn't understand the part where she has to actually wee!
She will wee in the potty, if she sits on it for a long period while playing or watching tv, but it's a coincidence.
She gets a chocolate button when she's done anything in the potty. We tried a sticker chart too. We've read various potty books with her - and she loves them. We've put pants on her, and tried the 'pants in the nappy' tricky, but she doesn't mind being wet.
How on earth do I help her to understand/care that she can't just wee on the floor? 
She is non-verbal and likely ASD to throw that into the mix, but very bright and understands what she is told. She knows the makaton sign for toilet.