Is this really right in japanese?

Question:

im trying to practice this right now im studying the grades and responding my favorite food is.. or my favorite color is..... but i tried saying this for example watashi wa hachi nen sei imasu would i put imasu or desu ? and another one i put is watashi no suki na tabemono wa spaghetti desu and watashi no suki na iro wa pinku,kuro,to shiro desu correct me please im still learning and please don't confuse me please

Answer:

>watashi wa hachi nen sei imasu
We do not say "hachi nensei" if you want to say "8th grade". We have 6-3-3 grade system in which we say 1st, 2nd and 3rd for each school.

So we would say "watashi wa chugaku ninensei ni imasu". You need to put "ni" before imasu.

>watashi no suki na tabemono wa spaghetti desu

This is correct.

>watashi no suki na iro wa pinku,kuro,to shiro desu

This is also correct.