Well you need to get a good routine going, and a good diet going. The diet is the hard part and sticking to it can be difficult. You need a good 6 meals a day and this can include some clean carbs' like Wholemeal bread, Pasta, Rice, Potatoes, and so on. You also need a good source of protein with the meal, such as Fish, Eggs, Steak, Chicken, Turkey etc.
At the moment I'm having 4 good meals and 3 protein shakes. If you are new to training you can train each bodypart twice a week if you like, as you will only be lifting small weights I imagine. I did this for about 8 months with really good gains, and now I am on once a week.
You can still create a great physique without joining a gym, although I think it's best if you can as you get to socialise etc, and you enjoy it more. But with the correct equipment at home you'll do just as good. Just make sure you are training intensly and focusing on the training, and not in between answering the phone and having a chat etc.
Here are some great videos on nutrition, and this same guy trains from home and let's be honest, he's in fantastic condition.
http://www.scoobysworkshop.com/
Have a read through it, he has loads of fantastic videos on nutrition and excersising at home. You'll learn a lot from him. I hope this helps,
Benni.