A row is one horisontal row in DrFront. A row can containt one or more articles. Don't add more articles in one row than necessary, UNLESS your intention is to build a more complex layout like two 50% articles in height, next to one article which has 100%. There are many other examples in which you need more articles in one row, but the point is to not have more than the articles needed in one row. Build your frontpage in rows in stead.
A container is a "locked" row that may contain one or more rows. This is useful if you need to copy and paste a set of articles up and down on your frontpage, or for design skining needs.
A locked container will not move in position (up or down) if you add another row at the top. It will always stay at row X no matter how many rows you add or remove.
An auto-row can be set by your developer or your administrator in the configuration. An auto-row is typically used for advertisement or external content that needs to stay untouched. An auto-row is non-editable for the front-end editor.