Most people buy fractions of bitcoin (btc) at a bitcoin or crypto exchange. There are lots of them. The best one for You is depending on your juristiction. After buying it on an exchange, You can send it to your own wallet. Like your wallet of Satoshi that You've setup now. Depending on how much You bought it's wise to look into the security to store it, so there are multiple ways to store your bitcoin. I'd advice You to go watch some tutorials on youtube about bitcoin and different ways to store it. In most towns people have bitcoin meetups too. Often it's monthly or weekly at a certain bar. Bitcoiners meet each other there and are often very willing to help others that are new to it. You can search online for bitcoin meetups near your town.

I hope that this helps You a bit.