If you use Tapatalk and want to create a new topic with your Nexus 7, follow these easy steps:
1. Tap "Forums" in the top menu bar
2. Drill down to your desired subject area. Note the the first two levels are reserved for forum layout, so you will have to be at the third level to reach the user access level to create a new topic.
3. Tap the three menu buttons in the right hand corner and tap "New Topic." Note if you do not see the "New Topic" option, you have not reached the user access level.
4. Enter the "Subject", then type your post, and tap "Submit."