You will have to determine your cost basis and your acquisition date. If you don't know the exact acquisition date you can estimate the date or you can enter "various". Just make sure you have the transaction properly classified as long term or short term. As for the cost basis, if you inherited the asset, your cost basis is the value on the date the deceased passed away. If it was a gift, your basis is whatever the cost basis of the donor was. If you cannot determine the cost basis or make a reasonable and conservative estimate you will have to use a cost basis of Zero.