nostr:npub1rxysxnjkhrmqd3ey73dp9n5y5yvyzcs64acc9g0k2epcpwwyya4spvhnp8 has everything you need to know on his YouTube channel.

Starting out you are fine with a software wallet for computer Sparrow wallet, for iOS or Android you can use Blockstream Green. There are many other but that is a good start.

Write down you seed phrase (your private key) and store it safely. Do not store a digital copy. This is how you recover funds if you ever lose access to your phone or computer.

Once you’re comfortable with that and you have more bitcoin to protect you can learn about hardware wallets (signing devices), passphrase, and multisig.

For buying if you are looking to protect your privacy you can go robosats but need to access over Tor. If not there are plenty of exchanges around just do not store large amounts on exchanges and know they track your bitcoin from that point onwards.