new to sti & need advice

STI is great, you can shift any end in any direction from the hoods or drops. 🙂 It's a little strange at first though, as you only see a brake lever and two paddles, and wondering where the other shifters are. The answer is that the brake lever itself is the "other shifter".

To upshift on the rear cassette, press the little paddle under the right brake lever. One press = one upshift.

To downshift on the rear cassette, move the entire right brake lever in the direction you'd have moved that little paddle (i.e. inwards, towards the centre of the bike.) Depending on how far you move, it'll shift up to 3 cogs at a time; there'll be a tactile click at each shift.

To upshift on the front chainrings, move the entire left lever as above. A full sweep will upshift the chainring, a partial sweep will go to various "trimming" positions (used to finely align the derailleur position, so that the chain doesn't rub on the cage.) NOTE: if you want a nice, clean shift, keep your pressure on the left lever until the shift completes.

To downshift on the front chainrings, press the little paddle underneath the left brake lever. There are intermediate stops for derailleur trim on this paddle too.

Just as Rek says.
It takes no time at all to learn except to listen out for the chain ring trimming. Again it comes very easily.
I'd been riding antiques before Nov 2003 and finally made the leap to STi.
What a difference it makes to cycling enjoyment. No more fiddling with the levers on the downtube and being in between gears.
Good luck although you won't need it.