Got keys to my car but

Well my mum got them yesterday but didn't tell me grr got up this morning she was at work and had left me list of jobs she wanted doing then told me to text her I did. She replyed have you done this and that. YES in the end I phone her as I guess she has hid the keys somewhere and she eventually tells me where they are. I get the car unlocked and theres a puddle on the floor of drivers side dry that up and start it up it goes backwards cos its in reverse first time I've ever done that mistake. Then it sounds like its not starting up theres a choke on it so no idea if thats anything to do with it not starting. Petrol meter stays on empty so that mite be it needing petrol. I have no idea. Maybe its the battery as the battery light comes on so I am going to charge it tonight and hope for the best. Thats if I can work out how to I'm clueless about cars.