Trading shares sheet

Hello, I want to make a basic spreadsheet showing wins and losses on the stockmarket. I'm just practicing on demo accounts and just want to try and get the hang of it so need a spreadsheet to see what I win/lose. Please help

Say COLUMN B represents BUY TRADES
In B3 I BUY shares at a price of 1000.
In B4 I type in the final price of the shares.
If the value increases to say 1100 then I've made 100 (and this +100 goes automatically into B5 and the box gets coloured green).

If the value of the shares decreases to say 700 then I've lost 300 (and B5 reads -300 and the box turns red).


Say COLUMN C represents SELL TRADES
In C3 I SELL shares at a price of 1000.
In C4 I type in the final price of the shares.
If the value increases to say 1100 then I've lost 100 (and this -100 goes automatically into C5 and the box gets coloured red).

If the value of the shares decreases to say 700 then I've made 300 (and B5 reads +300 and the box turns green).

Thank you

I'm new to speedsheets. Haven't got a clue. Pleae advise where to paste the formula etc