How can i get a set of songs onto one album on iTunes?

Well i downloaded an album but like when i go on album art scroll there all seperate and like when i add an album art to one song it should change for the rest but it doesnt.How can i get a set of songs onto one album on iTunes?Select all of the tracks of the album by clicking the first track, pressing and holding the shift key, then pressing the last track. Right-click the selection and click Get Info. Make sure that all of the album info is consistent. If any of the main fields (Artist, Album) is blank, the way that it's typed for each track is not exactly the same. Enter that info if the fields are blank. Also, enter the number of tracks in the second track field and 1 in both of the disc fields. Finally, paste the album artwork in the box for it and press OK.