I am just curious how one can download bitcoin data and blockchain using a node

One way is to download and install a full-node desktop wallet such as Bitcoin-core.

When it is first started it will download the full blockchain. This may take a week - depending on your Internet-connection's bandwidth.

Where should I start?

https://bitcoin.org/en/ is probably a reasonable place to start.

Ask questions here (one at a time) about any problems understanding or using Bitcoin. But use the search function here first - lots of great answers already exist for many problems.