I bought and sold some stocks on CashApp and I received a 1099 Composite form, on the top of this form there are the 1099-DIV, 1099-INT, 1099-MISC, and 1099-B boxes and all of them are zeros. after that, there are transactions details of buying and selling stocks and on the last page, there is the total Gain or Lose which says I gained $596, in this case, do I need to report this on Turbotax and if yes do I need to report all transactions or just the total lose/gain line?
Yes, you need to report these transactions. These are considered investment sales on the tax return. You should list each transaction, but if you choose you can enter summary totals. One for short term transactions, and if applicable, one for long term transactions.
When you choose to use the summary method you must take the following steps:
If you are e-filing your tax return, then mail your statements (and Form 8949 if it is in your tax return) along with Form 8453 to the following address within three days after the IRS accepts your tax return:
Internal Revenue Service
Attn: Shipping and Receiving, 0254
Receipt and Control Branch
Austin, TX 73344-0254
If you need a blank Form 8453, you can download this pdf, enter your address information and check the box for Form 8949 (this form is really just a cover sheet). TurboTax will provide the information and this form.