NGO Tax Exempt Registration

Hello

we have opened a Society for the welfare of the public, and we will be receiving Trust certificate after a year,

We wish to apply for PAN No & TAN No or A Registration No, which will help us provide Tax Exemption to our Donors,

Could someone provide me information, which forms needs to be filled to provide maximum exemption to our Donors, and NGO's also get 100% tax exemption certificate, what is the procedure to get them