To be fair, there is more than one Mary question.
Some don't get why we need to go to Jesus through Mary.
Some wonder why Catholics "worship" Mary. (We don't.)
Some don't get how we can "adore" Mary. (We don't.)
Some don't understand why we pray to Mary.
All big, valid questions.
For starters, we need Mary because Jesus needed Mary. In the manner that Jesus chose to come to earth, He needed Mary to carry Him and birth Him. Because He came as an infant, He needed Mary to nourish Him and bathe and clothe Him. Because He went through childhood, He needed Mary to take care of Him: cooking, cleaning, sewing, teaching---being a mom!
Picture this; A child walks into the house with a friend that s/he wants to introduce. Dad and mom are standing there and the child says, "Dad I want my friend to meet you. Chris, this is my dad." "Nice to meet you Chris", says Dad stretching out his hand. Mom is standing there, smiling, waiting.
Chris says, "Is this your mom?" To which the child replies, "Yeah, but she's not important. Let's go in the family room and talk with my dad for a while."
Christ did not make Mary's role, and her being, so important just to have us set her aside and forget about her now that her job of bringing Christ into the world is done. Her job of bringing us to Christ never ends.
We go to Jesus through Mary because she is the vessel through whom He chose to come to us.
Secondly, we don't worship or adore Mary. Worship and adoration are for God alone. We offer Mary something called hyperdulia. Click here http://centeredinchrist1.blogspot.com/2015/05/hyperdulia.html
to read my previous post on this subject.
Finally, why do we pray to Mary? Remember that prayer is conversation. When we go to Mary with our needs, we are asking her to take our needs to Christ. We are asking her to intercede for us. We do this for each other all the time. "Pray for me, please, I have a test to take." "Pray that I can find a good job," "Pray for my sister, she's going on a trip." We pray for each other all the time.
In the Old Testament, when Queen Mother, Bathsheba, went to see her son, King Solomon, he got up from his throne and bowed down to her (he honored her). (1 Kings 2:19)
Why was Queen Mother Bathsheba there to see King Solomon? She was there on behalf of someone who had asked her to talk to her son for him (to intercede for him). (1 Kings 2:19)
At the wedding feast of Cana, who knew the need of the couple? Mary did. What did she do for them? She interceded for them. "They have no more wine". (John 2:3) Jesus, ever willing to please His mother, performed His first miracle. Why would we not go to Mary when she has complete access to her Son at all times. She is more than willing to intercede for us at all times.
But there is more. What words did Mary say to the servant? "Do whatever He tells you." (John 2:5)
Mary leads us to Christ and His will. She still tells us to listen to Jesus and do whatever He tells us.
O Mamma Mary, O Queen Mother, O Mother of our Savior, pray for us, O holy Mother of God, that we make be made worthy of the promises of Christ. Amen