How to use a trailing stop

So I am tinkering with an Oanda demo. How to use a trailing stop. Like when I open a position, do I set a Take Profit and then set the Trailing Stop in place of a Stop Loss? Or something else?

TP is good for a trade heading towards support/resistance, especially something like a trade within a range. Not so good for a consistently trending price chart or where price has broken out to new highs/lows.

Choice between SL or TSL depends on the strategy. Worth trialling both in demo.