Who: Anyone who loves Jesus as Lord and Savior worships Him.
What: Worship is anything we do out of thanksgiving to God and adoration for Him.
When: Anytime you want
Why: Jesus lovers want to worship (or praise) God for who He is (perfect God) and what He has done (died on the cross for our sins).
How: Whatever comes naturally to you! You might worship best through singing about God or to Him, dancing out of joy, feeding the poor, making others feel welcome in your house, praying for or with others, being outside and realizing He's painted the sky, grew the flowers, etc. It can be drawing a picture to make Him smile, sharing your stuff, or telling someone about what God has done for you. Worship happens through more ways than we can name here. The concern is less about how you worship than it is about if you worship because God loves your worship.
How do you like to worship God?