Basics of trading

Good morning. I fell asleep last night doing the babypips school and woke in the early hours with questions buzzing around my head. I’m finding it fascinating so far but can someone confirm - if I think it would be good to sell because I think the price will fall 1. Can I just enter with a sale or do I already need to have bought? Is profit made when price falls if I sell before the fall ?

Yes, you may sell without bought anything before.
And yes, your profit is done, if you sold and close the trade (buy back) at lower price.