I think you'll have difficulty booking online flights departing from Nigeria ... a lot of airlines have restrictions on online of selling tickets departing from Nigeria (and other African countries too) due to high levels of card fraud.
You would be unlikely to be able to buy a ticket for someone else - the card holder would certainly have to travel
for example British Airways does not sell tickets from Nigeria online ... Virgin allows reservations to be made online but the card holder must be travelling and must pick up the paper ticket in advance of travelling.