First you have to check whether the Act is applicable to you or not. If you have more than 20 employees in your establishment which are performing on daily basis and the work is not of intermittent nature, then the Act has applicability on you.
For registration, You have to apply FORM 1 after making the initial payment as the receipt will be attached with the FORM application submitted. There are documents required to be attached alongwith the said FORM which would show the 1. Regisration/legal entity of the establishment; 2. Documents pertaining to PF and insurance 3. Other fees including security and licence fee.

once the above documents are complete and the FORM is complete in all respects, the registration is granted by the registering authority i.e. appropriate government.