Click on the index subtab in the Create Table tab. If there is a Primary Key then that index would automatically be created.
Index Name: A name can be given for the index, but it is not necessary. A default name will be provided.
Columns: Select the column(s) from the drop-down box on which you like to create the index.
To change the order of columns in the index, click on a column and click on the Up/Down buttons to move the column. Note that the order is applicable only for the Index. The column(s) in the table are NOT re-ordered.
Length: To index on a part of a column of Text data type (like Char, Text, Blob), enter the initial number of characters to be considered for Index in the length field. For example, when you enter 8, the index will be created on first 8 characters. If left blank, Index will be created on entire column. In case of BLOB data type, you must specify the length.
Index Type: Select index type from the drop-down. The index types are UNIQUE, PRIMARY, and FULLTEXT.
Visibility: Control the visibility of an index by selecting VISIBLE or INVISIBLE from the Visibility drop-down. Notice that by default indexes are visible. This feature is available for MySQL 8.0.11+ servers.
Click on Save to create the Index.