Depends a little on how and where you live

• Learning to grow some food (even just herbs on your balcony or windowsill)

You need a large enough container (bucket, bag, pot), with some holes for drainage (plants don't want to sit in water). It needs to be warm enough for the plant you want to grow, and moist enough. Getting the moisture right for seeds and plants can be tricky at first, it will get better with experience. There needs to be sufficient light, some plants need more than others. Research a few easy to grow plants and start with these. If you have little space, grow some kitchen herbs rather than vegetables, they increase the quality of your food by 99% and are expensive to buy, plus they are medicinal as well.

• Joining or creating a local sharing circle

Is there a preferred online portal where a sharing circle in your country might exist already? Facebook? Whatsapp? Telegram? A physical space somewhere? Search there first. If there's nothing, create the space yourself, as an online group, a sharing box in a public space, or an actual group of people you know.

For community sufficiently, groups like Buy Nothing and Everything is Free might be a small piece but they're a great place to start. They've been a wonderful way to shuffle resources to those who need them/can use them, and to build support networks within our community. I've met a bunch of my neighbors, made friends, and leaned on specializations and career experience from people in the group on various projects. I talk about them a lot over on the zerowaste and diy communities.