1. I am joyful because I have a prize.
> This sentence is correct.

2. I'm sick.
> This sentence is correct.

3. My foot has a problem.
> This sentence is correct.

4. The amazing spiderman game is fun.

> The amazing Spiderman game is fun.

(Spiderman is a proper noun so the first letter should be capitalize.)

~common noun "movie"       ~Proper noun "Spiderman"  

5. Ryan doesn't share toy.

> This sentence is correct or Ryan doesn't share his toys. 

6. On Monday, I showed a new toy to a teacher.

> On Monday, I will show a new toy to a teacher.

( If it is a future event we should use "will)

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Thank you so much Eric for doing your homework. You're getting better now. ^^ Please take good care of yourself and always study your Smart English book. See you on Friday.

~Teacher Cassie