This year, Erev Tisha B’av falls out on Shabbos. There are a number of unique laws:
There are differing opinions about learning Torah after midday. Ideally one should study sections that relate to the laws of Tisha B’av or the destruction of the Bais HaMikdash.
The regular seudas hamafsekes that is eaten before Tisha B’av (eating an egg etc.) does not take place. Rather, one may eat regular Shabbos food until the fast begins. One may eat Shalosh Seudos together with friends and family (if this what is normally done).
The fast begins at sunset.
All the other restrictions begin at nightfall.
One says the blessing on the candle after Shabbos.
The rest of Havdalah is not made until Sunday night after the fast. One who davens maariv should add ata chanantanu and one who does not should say, Baruch Hamavdil.
Havdalah on Sunday night consists of the bracha on the grape juice/ wine and the final bracha.
If one needs to break the fast they should first make Havdalah as it is described above. However, instead of grape juice or wine, it should be said with orange juice or coffee.