How do I know what 'Sales Section Title' to choose?When reporting gains and losses in my Brokerage account?

I think you're talking about the Box codes:  Short term is under a year, and the Long term is over a year

There are seven possible "Box" designations that indicate the holding period (Long/Short Term) and the reporting status. 

Code A. This code indicates a short-term transaction for which the cost or other basis is being reported to the IRS. 

Code B. This code indicates a short-term transaction for which the cost or other basis is not being reported to the IRS. 

Code C.  Short-term transactions for which you can't check box A or B because you didn't receive a Form 1099-B (or substitute statement).

Code D. This code indicates a long-term transaction for which the cost or other basis is being reported to the IRS. 

Code E. This code indicates a long-term transaction for which the cost or other basis is not being reported to the IRS. 

Code F.  All long-term transactions for which you can't check box D or E because you didn't receive a Form 1099-B (or substitute statement).

Code X. Use this code to report a transaction if you cannot determine whether the recipient should check box B or box E on Form 8949 because the holding period is unknown.