How to add an image to a post?

Hi,

How do I add an image in middle of a post and text there, like in between two paragraphs?
How about adding a link in the post, how do I do it…?
Obviously I need to some html right?
Then one more question, do I use the “text” box in widgets to add an image or banner to the side bar of the site? with html.
Learning to use word press here ??

Thanks!