I vote for 3 pictures... one of the bike (drivetrain side), a picture of your single speed cranks and an up close picture of your cassette. A 48 can be a tall chainring for a novice to push up a hill, so hopefully that picture will show a crank that can accommodate a shorter chainring. If not, your only bet would be a cassette with larger cogs... like a mountain bike, which is certainly an easy swap.

Short of these options, is it out of the question to sell your road bike and purchase one with a more typical double chainring up front? That 2nd ring would do wonders for your situation!