Welcome @uwbanjoman! Please make sure to quote your code and and provide a minimum working example–as is, we can’t tell what aa[13] is. What isn’t working for you?
You should be able to push! as many new rows as you want:
using DataFrames
df = DataFrame(a=1, b=2.0)
push!(df, (a=2, b=1.5)) # pushing a NamedTuple
push!(df, [5, 10.0]) # pushing a Vector