Welcome to Connect, @gigivandame. You mentioned that you’d like to follow the Cancer Support group. Simply by typing your first post, you should automatically be included in the group. However, there are a couple of ways to make sure.

Usually the first page you see when clinking into Connect is the page of Support Groups. Scroll down until you see Cancer Support. There’s a little oval outlined in blue which says Follow. Click that and you’re good to go. You’ll see new posts in that group.
However, Cancer support is pretty general. It will contain a host of many different types of cancer that may not be of interest to you personally.
If you’d like to narrow down the discussions you can search for the specific area which pertains to your concerns. Then, once you reply in that conversation you’ll notice a dark bell under the opening discussion. Clicking the bell shows you options to personalize how the notifications will come to you.

Are you being treated for or have a cancerous condition?