You can assign tags to organise records by following these four steps.
Step 1: Select the record

Inside the grid, double-click the record that you want to tag. A form will be displayed, as shown in step 2.
Step 2: Select the Tags command

On the ribbon of this form, select the command Tags.
Step 3: Choose the tag

Choose a tag from the list of available tags, or create a new tag by clicking on the new tag button.
To choose an existing tag from Available items, select the name of the tag or tags in the left-hand panel and click the Add -> button to include this tag in Selected items in the right-hand panel.
Finally, click Ok to finish.
Step 4: Select Save and close

Finally, click Save and close to finish.
Tags are displayed at the top so that you can see them whenever you open that record again.
OR
Alternatively, the same action can be performed by following these steps.
Step 1: Select Tag as...

Inside the grid, right-click on the record that you want to tag, and choose Tag as...
Step 2: Choose the tag

Choose a tag from the list of available tags, or create a new tag by clicking on the new tag button.
To choose an existing tag from Available items, select the name of the tag or tags in the left-hand panel and click the Add -> button to include this tag in Selected items in the right-hand panel.
Finally, click Ok to finish.