If you have enabled the option to accept payments through allevents.in, you will get the option to enter your Paypal details while setting up your ticketing.
Otherwise, you can head over you your event page, click on manage ticketing from the ‘Organizer Panel’ on top, scroll down and fill in your PayPal Account details.

The PayPal option will be available only if you choose one of the following currencies:

AUD Australian Dollar NOK Norwegian Krone MXN Mexican Peso
BRL Brazilian Real NZD New Zealand Dollar TRY Turkish Lira
CAD Canadian Dollar PHP Philippine Piso MYR Malaysian Ringgit
CZK Czech Koruna PLN Polish Złoty THB Thai Baht
DKK Danish Krone GBP Pound Sterling JPY Japanese Yen
EUR Euro SGD Singapore Dollar TWD New Taiwan Dollar
HKD Hong Kong Dollar SEK Swedish Krona USD United States Dollar
HUF Hungarian Forint CHF Swiss Franc ILS Israeli new Shekel