accused of using someone else’s credit card

It may be difficult for you to prove your innocence: (1) the shipping address was in your name; (2) the order was placed in your name; (3) since Nigeria is known to be a hotbed and hub of various kinds of financial, securities, credit card, telecom, and identy theft fraud, even saying that you were helping a "friend" in Nigeria who actually placed the orders may not help you--the assumption will be that were a voluntary participant in a scam.

That's not to say you should give up, but first and foremost, get an attorney to help you and gather together all your evidence that it was something you were doing, without compensation, for a friend--any emails, correspondence, etc. You want the attorney because in addition to possibly being on the hook for the mechandise, there may be criminal liability, too, if this is reported to law enforcement and they conclude you were a party.,

If the amount of money involved was trivial, you might want to just pay it while sending a letter reaffirming that you do not accept responsibility and were not a participant in what was going on, but are paying to just put this behind you. (However, your attorney can advise you whether he/she thinks this is a good idea.)

You also want to make sure you are NOT involved in anything going forward. If the store or vendor has not already contacted the credit card company behind this card, you should contact them and tell them that you believe the card is stolen and is being used to order materials in your name. You want to refuse all future shipments of good to you, unless you know for a fact it was something you ordered. You want to either immediately cut off all communication with this "friend" or possibly send one last registered letter or email indicating that they misled you and you do not want to be party to their actions or to ever have anything to do with them, and they may not order or ship goods in your name--the point of the letter is not that the criminal will necessarily believe you, but it may help to establish your good faith by showing that you're trying to extricate youself. Again, an attorney can advise you whether this will be helpful.

To reiterate yet again: credit card companies and law enforcement know that many frauds and scams originate from Nigeria. There is therefore a good chance civil and/or criminal action will be taken against you as a participant. Get an attorney, gather your evidence supporting your innocence, refuse further dealings, and never, ever get involved with overseas shipment of goods, money, or other assets.