What you calculated was for interest compunded annually (not monthly) for two years: $\displaystyle 800 \left(1+\frac {0.08} 2 \right)^2 = 933.12$. Scopur shows how to do it compounding monthly.
Find the accumulated value of an account of $800 at 8% compounded monthly for 2 years.
I keep getting the answer $933.12 which is wrong.
Im using the formula A=P(1 + r/t) ^nt
There's your problem! The formula is $\displaystyle P(1+ r/n)^{nt}$
r is annual interest and you are compounding monthly. If the annual interest is 8%= .08, then the monthly interest is $\displaystyle \frac{.08}{12}= 0.006667$.