Go to the Chatter object, select "Help & Training" in the group section of the menu on the left hand side.

This group is meant to be a place where users can ask questions and request assistance from other users. Under information: you can find a list of who to contact with specific needs. General questions can be sent to the whole group and anyone can reply if they have an answer. This will allow for the quickest response!

You do not need to go to the group's feed to pose or answer a question to the group. You can do it from the newsfeed on your home page by using @[Help & Training] in your post. This will ensure the post also appears in the Help & Training group, as well as in the newsfeed of any user who is a member of the group. 

If someone posts a question or needs help with a task and you can help, please respond. This group will work best if we all use it to share resources and answer each other's questions! You can do this by commenting on the original post  or by @ mentioning the person who asked the question in a new post.