A promising start, Khun Pipat. I feel the title needs a little revision. The correct way to describe this in English would be, 'How to wash hands healthily', which is perhaps not too snappy as a title. How about 'About Healthy Hand Washing', or something like that? ('hand washing' is the activity, 'healthy' is the adjective)
Your script is practically flawless, so I'm looking forward to a polished presentation. Just one point that the expression 'most of' is often misused. In your summary it should be 'Most Thai people' ('Most Thais' in the slide)
You should 'introduce' your visuals to the audience ('On this slide you can see...', 'Here we have ...', etc.) You can also point to the pictures to highlight your dialog.