Your husband needs to register as self employed and register for self assessment and he will need a trading name. 'joe bloggs builder/plumber ect will do.
He will be given a UTR number which will be unique to his business and also you will be given a code to access his account online through the government gateway. They will send you log on details by mail which will take about 5 working days.
Once you can log onto your account you can register for CIS. Once your OH is registered with CIS he will get a number which he will have to give to his sub-contractor (boss) Your OH will get tax taken off at source and at the end of the tax year when he fills in his self assessment return he will have to fill in the box to show how much Tax has been taken off -this is usually 20% of his gross pay. He will more than likely get a tax refund. If you are new to this it may be worth getting the advice of an accountant in filling in your first return as it can be complicated.