It helps if you include a link to the Series (Set) or at least the exact IMDb Title, which in this case is The Universe, not just Universe.
IMDb does not enter anything separately for Seasons (Series). Just click the Add Episode button near the bottom of the Series page, and enter the data for the first episode in the missing Season, giving it the Episode Number of 7.1. Repeat for each episode (in the Release Date sequence) incrementing the right part of the Number.
The Episode Number is of the format Season.Episode and IMDb uses this to separate the Episodes into Seasons.