How do I handle gains/losses that are on a list I received from an investment company? The gains do no appear on any of our "T" slips.

Enter your dispositions/sells in the Capital Gains & Capital Gains Deduction Profile of TurboTax. 

Go to the "Income" tab > "Investments" > "Capital Gains & Capital Gains Deduction Profile". Check the first box "Sold stocks, bonds, real estate, other capital property....", then proceed to provide the required information, selecting the correct "Type of capital property disposed of" that relates to your sale.