Now you should see your image and, after a few seconds, be able to right click it and copy the address.
Then you can paste it somewhere and surround it with
[img]
tags, such as
[img]https://i.imgur.com/gjSrEcd.png[/img]
If the address ends up looking like:
https://i.imgur.com/undefined.png
then you have to right click and copy the address again.. it doesn't seem to generate the proper address for the image right away. Sometimes the address will look longer:
blob:https://imgur.com/488acd9c-ca58-4e75-a3ed-e06f5568ff89
that won't work either. Whatever, just wait a few seconds before right click and copy image address.
Don't think there's a need to resize. The forums make large images smaller (and clickable to get bigger) automatically.
But if you want to be nice to people's internet connections, you can always put an h (stands for "huge" but isn't that huge") right before the .png or .jpg extension, like so:
[img]https://i.imgur.com/gjSrEcdh.png[/img]
versus
[img]https://i.imgur.com/gjSrEcd.png[/img]
They used to have buttons to do that, but they removed them...
Hope that helps and that it's not too annoying to use. At least it doesn't require an account..