You create a channel to someone by funding it with on-chain bitcoin and by linking to their address.
For instance, you can see mine here: https://mempool.space/lightning/node/024ff0d07634390efb131904b10a64cf2e3300574b51902d493a360fb522f486fc
1. Fund your node's BTC wallet by sending some to it.
2. Connect to the peer you want to establish a channel with - you just need their node's public key, address and port should they use a non-standard one.
3. Create a channel by binding your on-chain value associated to your node's wallet to that channel (aka. funding).
Now that the channel is established, it's total capacity equals the bound BTC value; meaning if that channel was funded with (converted) 500.000 sats, this is now it's max capacity. In fact, this is the kind of channel I have with Fishcake. Should I get zapped so hard that I would technically reach this limit, i could not receive any further zaps unless me or him were to increase the channel funding.
Should, for whatever reason, the channel close, then the accumulated value is split to their respective owners and transfered on-chain. However, this includes fees... So in most cases, you make a few channels, and that should do for a long, long time. I am FAR away from even reaching that 500k limit.
Thing is, as you can tell, you need some BTC before you can even get started. And this is a huge barrier of entry for many. I was SUPER lucky that Fishcake decided to build a channel with me. Absolutely amazing and I feel very fortunate for this. ^-^
That said, if you ask around here on Nostr, people will likely help you get a channel set up.
A channel is always based off an initiative; you *have* to create the channel - you can't just automatically receive it. Likewise, someone else has to have the initiative to build a channel to you.
I hope this helped!