Hi C.,
I was a preschool teacher for years and observed that kids develop their reading skills on a huge spectrum... some children read very early (three, four), some became proficient readers at 7 or so.
All that to say, this is one area not to sweat it too much.
My preschoolers loved playing with letters... I had a wooden alphabet puzzle where the letters come out separately. Letter magnets also work fine. We used them sometimes as 'cookies' and played bakery (they could select different letters) and hid them around the preschool -- the kids would find them, we'd say the name of the letter and then put it back into the puzzle.
We drew letters with sidewalk chalk. I cut out thick pieces of paper that had the first letter in their name and they could trace the shape with markers or decorate it how they chose. Cut out the letters of their name and let them glue them onto paper. You could even print out an alphabet a few times and let the kids cut and paste those. A lot of this is just about exposure. We can also make letter shapes with our bodies, which was a fun group activity.
And as everyone below has suggested: reading, reading, reading to them. Simple picture books with clear printing to follow along with your finger as you read. Read to them while they are playing with playdough. You can make letters with playdough as well. I read or told longer stories when the kids were busy with a fine motor activity (beading, playdough, coloring) if they liked. Offer a variety of sources, too-- in our family we will read and share magazine blurbs, online articles, non-fiction books on topics we enjoy... not just picture books. :)
Notice signs when you are out and about. Bananagrams tiles or an old Boggle game are great items to just have available to explore (don't play the games the way an adult would.)
I never had a 'how to read' curriculum; instead, I focused on offering experiential opportunities for children to familiarize themselves with letters and numerals.
For what it's worth, my son entered kindergarten not being able to identify every single letter and only some numbers. By first grade he was a strong reader and was choosing to read for pleasure on his own. We read a lot as a family as well and he has about an hour of reading time each evening, 20-30 minutes of a parent reading to him and another half hour, at least, of him reading independently.