is it a gerund or a participle?

i can't distinguish a gerund and participle so i need your help..

Growing things in the garden

if this sentence is the title of a book, is "growing" a gerund or a participle?

I saw you dancing
in this sentence is "dancing" a gerund or a participle?

i want to know which one is right and the reason the other one is wrong.
my english may be rude and bad but please understand. thank you!