Hello

Welcome to crypto community.
That is pretty simple. Basics are the same as you want to buy vegetables on a street market.
You need to transfer funds firstly on an exchange.
After you look for the coin you want to buy.
You can buy with existing proposals you see there or can put an order for your price (like - I'll buy this coin for this price). That is all
For better feeling, you need to try. Check for exchanges with demo tokens, so you can play with it