To 'give' a favourite, simply go on to the specific user's entry, and then click on the 'love heart' icon that can be found just below the entry on the right.
Be careful though as once they are given, you can't take it back!
After giving a favourite, you must then wait 24 hours until the next favourite will be available.
If you are a member with five favourites to give, you will be able to give another favourite immediately until all five are used, and then after 24 hours the first favourite will have been replenished.
For example, if you give a favourite at 3pm, 4pm and 5pm, your next favourite will be available at 3pm the following day.
You can only favourite a journal entry once.