To make the grass: Hold tip #233 straight up over the cupcake. Starting very near the surface, squeeze. While squeezing, pull straight up. If you pull at an angle or to the side your grass will look weird.
Cakes By Carol Top tip - to get grass effect I bought a normal household scrubbing brush (I did have a smaller one but took some time to do the board) they don't cost much and I've also used it for sand and teddybear furr! Just wash in warm soapy water after each use