Unfortunately, there is no way to get a free Club Penguin membership. Club Penguin accounts are free for everyone, but Club Penguin memberships must be paid for.
Club Penguin offers various membership packages that account members can select. A Club Penguin membership costs $5.75 in US Dollars for one month and $7.95 for every month after the initial one. A six month membership costs $29.95 for the first sixth months and $39.95 for each recurring sixth month period after the initial six months. The most expensive and lengthy membership package is for a one year membership and costs $44.95 for the first year, as well as $59.95 each recurring year after.