i would think tutorials would be perfect for you.
they are generally short, and cover a very specific topic. seems to me that would be the way to keep your attention, right?
php is extremely popular. theres tutorials that range from the extreme basics of php, all the way up to some fairly advanced things.
remember, a large part of learning is learning things you dont need to know right at that moment. imo the best learning comes from when you start to take the bits and peices you know, and start experimenting with them and seeing what works and what doest.
try to do things on your own. when you get stuck, search for an answer. if you have made an effort to find an answer on your own and cant solve your problem, come to a message board such as this and ask for help on the specific problem your having.
have you started coding yet? i would think doing the actual coding part wouldnt lose your attention. if it does, maybe programming is not right for you. programming/scripting requires good concentration most of the time.