I've never used ReCharge myself, but if you don't have to use it here unless you want to. You can buy vouchers from various retailers such as Walmart (I believe Canadian Tire too) and pretty much anywhere that sells Public Mobile SIMs. If you have a credit card, you can set it up with that too and if you want it will pay for the service automatically each month (and give you a discount). I believe you can also use prepaid Credit Cards as well although tend to have an activation fee, they are reloadable if you do not have a credit card or don't want to put it online.
For Recharge themselves, you just go to their website, find Public Mobile and buy the amount you want (you also pay a fee) they will send you a code and you can use that code to add the funds to your account. For your $40 account, you will need to press the Show All button under the ones it shows by default.
