Sort:  

I don't think it's possible to update profile picture yet.
As for following, you just click on the account name of the person who posted or comments and it drops down to allow you to click [Follow].
Alternative, if you know the account name, you can go to the page and there'll be a [Follow] somewhere at the top right and you click that.


Then you see at the top right, there'll be 2 icons: Follow and Mute.
Then post of the people you follow will appear in your Feed/Home at

Hope that helps. For example, my account name is @ace108. So, my page will be: https://steemit.com/@ace108 https://steemit.com/@meiks/feed

2 months ago, someone asked and I don't think anything change. See?
https://steemit.com/steemit/@writewords/why-doesn-t-steemit-have-profile-pics