You said "DSPP" not "ESPP", didn't mention any discounted purchase price or say anything about receiving Form 3922, so I'm guessing this is plain-vanilla stock, stock that's not a bit different than a stock you might purchase through your broker. So you pull out your record of purchases and fire up your spreadsheet to calculate the basis. If you didn't make an election before the sale settled to use a different method of calculating basis, then FIFO is the default method.
Depending on how much stock you sold your 1099-B could have different sales categories such as long-term noncovered, long-term covered and short-term covered. If that's the case the you should have to only determine the basis for the long-term noncovered portion.
Use the "Stocks,Mutual Funds, Bonds, Other" interview. For date acquired you can use the word "various"; the holding period for the sale is determined by the sales category you select.
