First, have a look at this topic that describes the various categories within the forum & where to post:
Secondly, in order to respond to a topic or create a topic, you need to be at “Trust Level 1”. What are trust levels? - this topic explains:
As I write this, you are at Trust Level 0. In order to advance to Trust Level 1, you must:
Enter 5 topics
Read 5 posts
Spend at least 15 minutes reading posts
I’d suggest reading this topic that might address your question about the Garmin g1000:
Once you are at trust level 1, you can reply to that topic, or if it does not answer your question, create a new topic in User Support HubAircraft & Systems