The most basic ways to build a playlist and play a full album, just use drag and drop.

It is also possible to add albums to the playlist by (double)clicking the covers or the info text. This depends on the predefined action. Actions to be executed by (double)clicking elements in the main interface can be defined in the Actions page of the Preferences dialog.  At the same page you also define if you want to use either click or double click to perform the actions.

Detailed album info can be shown by (double)clicking a cover in the grid (default action after fresh AP install). In the basic skin, the info window is visualized as a booklet. If Show Album Info is not defined as a (double)click action then you can right click on the cover and choose the option from the menu.  The info window contains 4 pages, described in Show abum info. The first page contains functions to add or play the album or individual tracks. For both the album and for the tracks there are buttons to Add tracks to playlist, Play tracks or Play tracks as next.

If you want to insert tracks to the playlist or reorganize track order, you can drag and drop tracks.